Automatic focus control camera

ABSTRACT

In an automatic focus control camera capable of obtaining a focus control information during focus adjustment comprising focus control information obtaining means requiring a time between the sensing of the focus condition and the generation of data indicative of the necessary degree of focus adjustment, and modifying means for modifying the data with a degree of focus adjustment expected to occur with a predetermined speed during the time, there is provided means for interrupting the operation of the obtaining means and the modifying means for a period beginning from the initiation of focus adjustment.

FIELD OF THE INVENTION

The present invention relates to an automatic focus control having anarrangement for obtaining various information to provide an automaticfocus control and adjust a lens of the camera to an in focus positionautomatically based on the obtained information.

DESCRIPTION OF THE PRIOR ART

There have been proposed many kinds of automatic focus control camerasof the above type. However, in the conventional autofocus cameras thereare still many problems to be solved. First, it is necessary to obtainreliable information for performing the automatic focus control. Second,it is necessary to provide a practical driving of a motor forpositioning the lens in the in focus position in response to theinformation. With respect to the second issue, it is necessary to movethe lens to the in focus position with a minimum loss based on theobtained data, to decrease the time for positioning the lens at in focusposition, to determine whether the lens is at the in focus position andto process the obtained information in case the obtained information isnot suitable for the lens attached to the camera. Third, it is requiredfrom the point of view of manufacturing the cameras how to perform thevarious adjustments of the camera during the manufacturing process toassure an accurate performance of the camera.

In studying the first problem, conventionally, there have been knownfocus adjusting devices in which the various informations are obtainedfor the automatic focus control by receiving light which has passedthrough an interchangeable lens and a diaphragm aperture opening. In thefocus control device of the above type, the necessary information cannot be obtained in case the minimum F Number of the interchangeable lensis not smaller than a limit minimum F Number required in the automaticfocus control device. Against this drawback, there has been proposedsuch an arrangement that the minimum F number of the usedinterchangeable lens is sent to the camera body then the focus detectionis inhibited if the sent minimum F number is greater than the limitminimum F number required in the device. However, there areinterchangeable lenses that has a minimum F number which is variedcorresponding to zooming and/or focusing. In case an interchangeablelens of the above type is used, the automatic focus control will beenabled or disabled depending on the change of the minimum F number ofthe lens corresponding to the state of the focusing or zooming, wherebythe user may be perplexed.

In studying the second problem, the conventional automatic focusdetection device has such problems as follows;

(1) The focus detection device can not obtain the necessary informationfor the automatic focus control from an inadequate condition of aphotographic object, such as a low contrast. As the countermeasureagainst this problem, one proposed device is so arranged that when thefocus detection is disabled for a lens position, the lens is forciblymoved by a predetermined length so as to seek whether or not there isanother lens position where the focus detection is made possible.However, in this arrangement, if there happen to occur a condition thatthe focus detection is disabled during the progress of the normalautomatic focus control, toward a just focus position the operation ofthe lens movement is inadvertently changed to the seeking operation fromthe normal focusing, whereby an unnecessary lens movement is interposedin the desired focus control.

(2) Another arrangement is to obtain the necessary informationrepeatedly. In this arrangement, if the information sequentially takenin the camera is erroneous due to movement of the camera, and theautomatic focus adjustment is performed in response to the erroneousinformation, the lens is unnecessarily moved to and fro.

(3) Generally it takes time before the necessary information becomesavailable in the lens control circuit after the light measurement of thephotographic object is made. Thus, in a system in which the focusdetection is made during the lens movement, an error occurs between thelens position at which the light measurement is made and the lensposition at which the information used in the lens control circuitbecomes available, due to the lens movement during the internal time. Inorder to compensate for this error, conventionally a correction of theinformation taken is made by means of amending the information with aconstant value corresponding to the lens movement during the internaltime. However, it takes a certain amount of time before the lensmovement reaches a stable speed in the beginning of the lens movement.Accordingly the amount of the lens movement during the time with thestable speed and the amount thereof under the unstable speed aredifferent, whereby an accurate focus control can not be expected if theinformation for the focus control is amended by the constant value asemployed in the prior art.

(4) In the process of the focus control, conventionally, the motor isdecelerated when the lens reaches a predetermined position near the infocus position to achieve a smooth stop of the lens movement. However,if the motor speed is different at the position at which thedeceleration begins, the length of lens movement from the beginning ofthe deceleration till the deceleration to a desired low speed of lensdiffers. In fact the lens may reach the near focus position with astable high speed or may reach the near focus position directly afterthe lens begins to move with a relatively low speed. Therefore, if thedeceleration of the motor is inadequately made to increase the time forlow speed lens movement, the rapid focus control can not be expected.

(5) As has been stated above, it is essential to decelerate the lens inthe near focus condition to prepare the smooth stop of the lensmovement. In case the focus control is performed when the object itselfis moving to and fro, however, there may occur the near focus conditionand the far focus condition alternatingly due to the movement of theobject to correspondingly change the speed of lens movement. If the lensis moved with a high speed or low speed alternatingly corresponding tothe near focus and far focus conditions, the smooth movement of the lensmay be deteriorated.

(6) Conventionally, it is employed to determine whether or not the lensis positioned in the in focus position by detecting that the lens issituated in a predetermined allowable range which is regarded as the infocus position. However, still a problem exists in determining how todecide the allowable range.

(7) It is strongly desired to position the lens in the in focus positionrapidly. However, the conventional automatic focus control is still notenough in complying with the above requirement.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an automatic focuscontrol camera which is able to complete the focus control rapidly witha smooth movement of the lens.

Another object of the present invention is to provide an automatic focuscontrol camera which is able to perform an accurate focus control.

A further object of the present invention is to provide an automaticfocus control camera which is enabled to move the lens based on the bestpossible information without any undesired movement.

A still further object of the present invention is to provide anautomatic focus control camera which is able to effect a smooth lenscontrol even if a photographic object is moving.

A still further object of the present invention is to provide anautomatic focus control camera with an improved operativity in theactual use.

According to a feature aspect of the present invention, in an automaticfocus control camera capable of obtaining a focus control informationduring focus adjustment comprising focus control information obtainingmeans requiring a time between the sensing of the focus condition andthe generation of data indicative of the necessary degree of focusadjustment, and modifying means for modifying the data with a degree offocus adjustment expected to occur with a predetermined speed during thetime, there is provided means for interrupting the operation of theobtaining means and the modifying means for a period beginning from theinitiation of focus adjustment. By this arrangement, at the initialstate of the focus adjustment, an erroneous focus adjustment due towrong modification of the data can be prevented and the modificationmeans can be effectively used.

According to another feature of the present invention, in an automaticfocus control camera in which when the remainder obtainable bysubtracting actual degree of focus adjustment from the necessary degreeof focus adjustment is less than a reference data, the driving power isreduced, the reference data can be changed corresponding to thenecessary degree of focus adjustment. Accordingly, in case the remainderis made small before the speed of the focus adjustment becomes highsince the necessary degree of focus adjustment is small, the referencedata is made small so that the power reduction may be made at a positionnearer the in focus position. By this arrangement, it can be avoided theproblem that it would take a long time for the focus adjustment due toany unnecessary early reduction of the power to the motor.

According to a further feature of the present invention, in an automaticfocus camera in which the driving power for moving the lens is reducedwhen the degree of the defocus becomes less than a reference level, thereference level is changed from a first reference level to a secondreference level which is greater than the first reference level when thedriving power is once reduced, whereby once the driving power isreduced, even if the degree of the defocus becomes large again due tothe movement of the photographic object, the reduction of the drivingpower is continued so that a smooth focus adjustment can be assured.

According to a further feature of the present invention, in an automaticfocus control camera in which the information for the focus control isnot reliable, a search for another focusing position at which a reliablefocus information is obtainable, there is further provided a disablingmeans for disabling the search operation even if it is suddenly decidedthat the information is unreliable when the focus adjustment is beingpracticed toward the in focus position. By this arrangement, undue focusadjustment can be prevented during the process of the focus adjustmentto the in focus position.

According to a further feature of the present invention, there isprovided a causing means for effecting the focus adjustment based on newinformation when an abrupt change between the successively obtainedinformation occurs due to such as a camera shake without responding tothe abruptly changing information. By this arrangement, an unnecessaryfocus adjustment due to the abrupt change of the information can beprevented.

According to a further feature of the present invention, when ateleconverter is used, a range of permissible defocusing which can bedealt with as in focus conditions may be expanded compared to the casewhen the teleconverter is not used. In general, when the teleconverteris used, even if an object situated at the same distance moves the samedistance in the direction of the optical axis, the amount of change ofthe defocusing degree may be large compared to the case when theteleconverter is not used. Also, when the teleconverter is used, theeffective F number changes to increase the depth of focus compared tothe case when the teleconverter is not used. Considering the abovematters, by expanding the range of permissible defocusing degree withthe presence of the teleconverter a reasonable decision on the focus canbe made.

According to a further feature of the present invention, focusadjustment is continued until the actual exposure to the film isinitiated even after the operation of the exposure is set. By thisarrangement, the time available for the focus control can be extendedcompared to the conventional arrangement in which the focus adjustmentis stopped when the operation of the exposure is set about even if thetime length between the initiation of the focus adjustment and actualexposure to the film is the same, thereby enabling a more suitable focusadjustment. In other words, the time from the completion of a suitablefocus adjustment till the actual exposure to the film can be shortened.

According to a further feature of the present invention, in a camera inwhich, the information obtaining function is prohibited, when theminimum aperture value of the interchangeable objective lens is greaterthan a limit, in case the effective aperture value of theinterchangeable lens with the diaphragm aperture fully open changes dueto zooming or focusing, said interchangeable lens is provided with meansfor outputting, independently from the actual variation of the effectivefully open aperture value, a signal indicative of the minimum of thevariable effective aperture value with the the diaphragm aperture fullyopen. In case such interchangeable lens is used, since it is completelyprohibited to obtain the information for focus control when the signalis greater then the limit, it can be prevented to confuse the user witha change between the enabled and disabled conditions of the automaticfocus control in the process of using the camera.

According to a further feature of the present invention, in a camera inwhich means for obtaining an information of focus condition iscontrolled by sequence control means for controlling the total cameraoperation sequence, said obtaining means can be controlled without saidsequence control means by selecting a possible operation mode. By thisarrangement, the obtaining means can be enabled in the manufacturingprocess for its adjustment, so that a disadvantage that the obtainingmeans of the camera can not be adjusted until the sequence control meansis mounted in the camera is eliminated. In addition after the camera isentered in the market, the operation of the obtaining means can beadjusted or inspected independent of the total camera operationsequence.

According to a further feature of the present invention, in a cameracomprising means for providing driving power corresponding to theinformation for focus control and means for informing said informationsensibly, whereby the automatic focus control mode in which theproviding means is operative and the manual focus control mode in whichthe providing means is inoperative can be selected as desired, under themanual focus control mode, the sensibly information means is enabled bymanipulating either a manually operable member for a shutter releaseoperation or another manually operable member for the exposureinformation setting, and under the automatic focus control mode, saidproviding means can be enabled only when the manually operable memberfor the shutter release operation is manipulated. The manual focuscontrol can be performed by a manual focus adjustment in associationwith information obtained by the sensibly informing means. Therefore, itis desired that the sensibly informing means is already enabled when theuser of the camera wishes to perform the manual focus control. By thearrangement as described above, since the sensibly informing means isalready enabled by the manipulation of the manually operable member forthe exposure information setting which is expected to be practiced priorto the focus adjustment, the user of the camera directly can perform thefocus adjustment without a further operation for enabling the sensiblyinforming means by means of the manipulation of the manually operablemember for the shutter release operation. On the other hand, under theautomatic focus control mode, it is desired to begin the automatic focusadjustment when the user of the camera sets the shutter releaseoperation. On the contrary, if the automatic focus adjustment beginsupon the exposure information setting, the user of the camera may beconfused. According to the feature of the invention said providing meanscan not be enabled by the manipulation of the manually operable memberfor the exposure information setting so that the confusion describedabove can be effectively prevented.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 comprised of FIGS. 1(A) and 1(B) is a schematic diagram showing acircuit arrangement of an automatic focus control camera according tothe present invention,

FIGS. 2(A)-2(H) and 3(A)-3(E) are flow charts showing the operation ofthe circuit arrangement shown in FIG. 1,

FIG. 4(A) and 4(B) are a schematic diagram showing the details of blocksLEC and COV of the automatic focus control circuit shown in FIG. 1,

FIG. 5 is a schematic diagram showing the circuit relating tomicrocomputer MC₂ of FIG. 1 when it is operated independently frommicrocomputer MC₁ and

FIGS. 6(A)-6(E), 7(A)-7(F), 8(A)-8(G), 9(A)-9(F), 10(A)-10(D), and11(A)-11(D) are flow charts showing the operation of microcomputer MC₂in association with FIGS. 1 and 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a circuit diagram showing a whole camera system according tothe present invention. In the FIG. 1, BA denotes a D.C. power battery,the driving power is supplied through a driving power line +E to amicrocomputer MC₁ for controlling, a microcomputer MC₂ for detecting andadjusting a focal distance (the microcomputer MC₂ is called the AFmicrocomputer in the following), a display unit DSP, a buffer circuitBF, NOR gates NO₀, NO₁, a NAND gate NA₁, respective pull up resistersfor pulling up for switches S₁, S₂, S₃, TSS, ASS, ISS, MOSS, UPS, POS.

S₁ denotes a switch for measuring a brightness of an object, which isclosed when a shutter release button (not shown) of the camera is pusheddown to a first depth. When the switch S₁ is closed, the output of theNOR gate NO₁ goes down to "Low" and the operation of the microcomputerMC₁ for controlling is set about after an interrupt signal is inputtedto an interrupt terminal it₀ in the microcomputer MC₁. The switch TSS isclosed when an exposure time is changed. (The switch TSS is called theTv switch in the following.) The switch ASS is closed when an effectiveaperture value is changed. (The switch ASS is called the Av switch inthe following.) The switch ISS is closed when a sensitivity ISO of aused film is changed. (The switch ISS is called the Sv switch in thefollowing.) The switch MOSS is closed when an exposure control mode ischanged. (The switch MOSS is called the mode switch in the following.)When these switches TSS, ASS, ISS and MOSS are closed, an output of aNOR gate NO₁ goes down to "Low", whereby an output of the NOR gate NO₁down to "Low", and the interrupt signal is also inputted to theinterrupt terminal it₀ of the microcomputer MC₁ and the operation of themicrocomputer MC₁ is set about. UPS is a switch for increasing data.(The switch UPS is called the UP switch in the following.) DOS is aswitch for decreasing data. (The switch DOS is called the DOWN switch inthe following.) S₂ is a release switch which is closed when the shutterbutton is pushed down to a second depth which is deeper than the firstdepth. S₄ is a reset switch, which is changed over to a terminal EEafter the exposure controlling operation is completed. Said switch S₄ ischanged over to a terminal WE after charging in an exposure control modeis completed.

FIGS. 2 and 3 are flow charts showing the operation of the microcomputerMC₁. In the following, referring to FIGS. 2 and 3, the operation of thecamera system in FIG. 1 will be described. When the driving power issupplied through the driving power line +E after the battery BA ismounted in the camera, the microcomputer MC₁ is set about from the step#100 in FIG. 3. First of all, at the step #100 ports P₂₂, P₂₃, P₂₆, P₂₉and P₃₁ ˜P₄₀ of the microcomputer MC₁ are designated as an input mode,and at the step #101 ports P₂₀, P₂₁, P₂₄, P₂₅, P₂₇, P₂₈, P₃₀, P₄₁, P₄₂and P₄₃ designated as an output mode. The ports P₂₀, P₂₁, P₂₄, P₃₀, P₄₁,P₄₂ and P₄₃ designated as the output mode are initialized "High". On theother hand, the ports P₂₅, P₂₇ and P₂₈ designated as the output mode areinitialized "Low". The microcomputer MC₁ acts to stop the generation ofreference clock pulses STCL from a terminal STCLOU. Then a flag CDFF isreset and a mode register MOR is set by "0". The flag CDFF is set to "1"when a computation of the exposure control value is completed. Underthis state, the content of the register MOR is set by the datadesignating the exposure control mode, wherein "0" designates a programexposure control mode (referred to as a P mode in the following), "3designates an automatic control mode of adjusting the effective aperturevalue with an exposure time priority (referred to as a S mode in thefollowing), "2" designates an automatic control mode of the exposuretime with adjusting the effective aperture value priority (referred toas a A mode in the following), "1" designates a manual setting mode ofadjusting the effective aperture value and the exposure time (referredto as a M mode in the following). Next, at the step #107, the data ofthe film sensitivity ISO 100 (Sv=5) is set in a register for filmsensitivity data TSR, then the data of F5.6 (Av=5) is set as a settingeffective exposure value Avs at the step #108 and the data of 1/60 sec(Tv=6) is set as a setting exposure time Tvs at the step #109. At thestep #110, it is displayed in the display unit DSP that the exposuremode is the P mode and the film sensitivity is ISO 100, the display ofthe effective aperture value and the exposure time are blanked , and theoperation of the microcomputer MC₁ is stopped after it is inhibited forcounters in the microcomputers to interrupt an interruption permissionsignal is inputted to the interrupt terminal it₀.

When one of the switch S₁ for measuring the brightness of the object,the Tv switch TSS, the Av switch ASS, the Sv switch ISS and the modeswitch MOSS is closed, the microcomputer MC₁ is set about from the step#0 in FIG. 2 after the interrupt signal is inputted to the terminal it₀in the microcomputer MC₁. At the step #0, the driving power is suppliedfrom the driving power line +V after making the terminal P₃₀ "Low" atransistor BT₀ is turned on through the output of the buffer circuit BF.Next, the reference clock pulses are outputted from the terminal STCLOUto the AF computer MC₂, an interface circuit INF and a motor controlcircuit MCC. At the step #2, the content of a counter for the counterinterruption in the microcomputer MC₁ is reset and the counterinterruption is permitted, then at the step #3 the data of theexchangeable lens mounted in the camera is taken in.

Referring to FIG. 4, a way of reading data of the mounted lens will beexplained. In the lower part of the left hand side of FIG. 1, a blocksurrounded by one dashed chain line is the circuit diagram provided inthe exchangeable lens, wherein COV is a converter circuit for use insuch as a teleconverter lens arranged between the body of the camera andthe exchangeable lens. One example of these circuits are shown in FIG.4. When the microcomputer MC1 reads the data of the lens, the terminalP₂₈ is made "Low" and the microcomputer MC₁ cancels the reset conditionof counters CO₀, CO₁, CO₂, CO₃ and T type flip flop TF₀, TF₅. Next, thecomputer MC₁ performs the input and output operation in series, that is,the eight pulses of the serial clock SICK are outputted from theterminal SICK₁, the counters CO₀ and CO₂ count the said clock pulsesthrough the inverter IN₀ and IN₁. Decoders DE₀, DE₂ make "High"terminals d₀ ˜d₇ in turn and make respective AND gates AG₀ ˜AG₇ and AG₁₀˜AG₁₇ enable state, then the decoders DE₀, DE₂ output the data outputtedfrom ROMs RO₀ and RO₁ in series in turn from the lowest bit through ORgates OG₀, OG₂. The Q outputs of the respective T type flip flops TF₀and TF₅ become "High" at the positive edge of the eighth clock pulse (atthe negative edge in the output of the inverter) after terminals b₂ ofthe counters CO₀ and CO₂ goes down to "Low". After that, the Q outputsof the T type flip flops TF₀ and TF₅ become "Low" at the positive edgeof the next clock pulse. Then the counter CO₁ counts the said negativeedge of the Q output of the flip flop TF₀.

                  TABLE 1    ______________________________________    b.sub.7        b.sub.6              b.sub.5                    g.sub.3                        g.sub.2                            g.sub.1                                g.sub.0                                    Address Data    ______________________________________    0   0     0     0   0   0   0   00H     Check data    0   0     1     0   0   0   1   01H     Minimum F number                                            Avo    0   1     0     0   0   1   0   02H     Maximum effective                                            aperture value Avmax    0   1     1     0   0   1   1   03H     Minimum F number                                            AFAvo for the AF                                            operation    1   0     0     0   1   0   0   04H     Eclipse data 00H    1   0     1     1   0   0   0   000*****                                            Conversion factor kL    1   1     0     1   0   0   1   001*****                                            Focal length fv    1   1     1     1   0   1   0   010*****                                            Changed in aperture                                            value according to                                            zooming dAv    ______________________________________     *****Output of zoom code plate

                  TABLE 2    ______________________________________                            Ad-    b.sub.7        b.sub.6              b.sub.5                    e.sub.1                        e.sub.0                            dress                                 Data     Output data    ______________________________________    0   0     0     0   1   80H  *        Check data    0   0     1     0   1   81H  *        Avo    0   1     0     0   1   82H  *        Avmax    0   1     1     1   0   83H  80H+dAvc AFAvo+80H+dAvc    1   0     0     1   0   84H  Avoc     Avoc    1   0     1     1   0   85H  kC       kL+kC → kL    1   1     0     1   0   86H  fvc      fv+fvc → fv    1   1     1     1   0   87H  dAvc     dAv+dAvc → dAv    ______________________________________     *The data are transferred from the lens to the body of the camera.

                  TABLE 3    ______________________________________    b.sub.7          b.sub.6    b.sub.5                           Address     Data    ______________________________________    0     0          0     00H         Check data    0     0          1     01H         Avo    0     1          0     02H         Avmax    0     1          1     03H         AFAvo    1     0          0     04H         00H    1     0          1     05H         kL    1     1          0     06H         fv    1     1          1     07H         00H    ______________________________________

Table 1 shows the correlation between the outputs of the counter CO₃ andthe decoder DE₃ and the address and data of ROM RO₁ in a lens circuit LEin case the interchangeable objective lens is a zoom lens. Table 2 showsthe correlation between the outputs of the counter CO₁ and the decoderDE₁ and the address and data of ROM RO₀ in the converter lens COV.

Table 3 shows the relation between the address and the data in case theinterchangeable objective lens is a lens with a fixed focal length incomparison with Table 1.

In Tables 1, 2 and 3, the check data is the common data in all kinds ofthe lens to be mounted to the camera, which is used for checking whetheror not the interchangeable objective lens suitable for the system of thepresent embodiment is mounted properly to the body of the camera. Avo isa fully open aperture value at the shortest focal length (which is thesmallest fully open aperture value) in case the used interchangeableobjective lens is a zoom lens which changes the effective aperture valuecorresponding to the change in focal length, and Avo is also a fixedfully open aperture value in case the interchangeable objective lens isa lens such as a lens with a fixed focal length or a zoom lens, whichdoes not change the effective aperture value according to the change infocal length. Avmax is the maximum effective aperture value, which isthe fixed maximum effective aperture value or the maximum effectiveaperture value at the shortest focal length, similarly in the case ofthe fully open aperture value. When the lens is mounted on the camerathrough the converter lens COV, the three data are directly transferredto the camera because the data are outputted through the AND gate AN₂and the OR gate OR₁. In Table ₂, "address" and "data" represent theaddress and the data in the ROM of the converter lens COV, and "outputdata" represents the data transmitted to the camera body from theconverter lens COV.

AFAvo is the minimum F number relating to the detection of aninformation for automatic focal control through the lens and itsdiaphragm. AFAvo is identical with Avo when the interchangeableobjective lens is a lens with a fixed focal length or a zoom lens withits effective aperture value unchangeable in response to the zooming.And AFAvo corresponds to a fully open aperture value at the longestfocal distance (which is the greatest fully open aperture value) in casethe interchangeable objective lens is a zoom lens which changes theeffective aperture value in accordance with the zooming. Moreover, AFAvocorresponds to the greatest fully open aperture value in case theinterchangeable objective lens is a lens which changes the effectiveaperture value in accordance with the focusing. The data of AFAvo isoutputted after it is added to the data 80H+dAvc from the ROM RO₀ in theconverter lens COV in the serial addition circuit ARC if the converterlens COV is used. dAvc means the change in the effective aperture valuecaused by using the converter lens COV, 80H represents that theconverter lens COV is mounted by the data "1" in the most significantbit of the one byte data.

Next, OOH is outputted from the ROM RO₁ in the lens LE and Avoc isoutputted from the ROM RO₁ in the converter lens COV, both as an eclipsedata. The eclipse data means a threshold value of the effective aperturevalue that the incident light to the body of the camera through the lensis eclipsed by the converter lens COV when the converter lens COV isarranged between the interchangeable objective lens and the body of thecamera. Therefore, when the converter lens COV is mounted, the botheclipse data are added and the eclipse data Avoc, which is the sum ofthe addition, is inputted to a circuit arranged in the body of thecamera. In case the converter lens COV is not mounted, the data OOHoutputted from the lens circuit LE is inputted to the circuit in thebody of the camera. A conversion factor kL predetermined in the usedlens is outputted from the ROM RO₁ in the used lens, which means theconversion factor to convert from a defocused quantity of the lenscalculated by the AF microcomputer MC₂ to the the number of the rotationof the AF motor for controlling a position of the optical system for theautomatic focus adjustment. The defocused quantity is representative ofthe difference between the position of the image of an object to befocused and a surface to which the image should be in focus. Thedefocused quantity is measured by a focus detecting device provided inthe body of the camera. The degree of the rotation of the AF motor (themotor for automatic focus control) necessary to reduce the defocusingquantity to zero by means of the focus adjustment caused by the AF motoris different in each interchangeable objective lens. The factor used inconversion of the defocusing quantity into the degree of the rotation ofthe AF motor is referred to as the conversion factor. As the data of theconversion factor kL changes in accordance with the focal length in azoom lens, the data representing the conversion factor kL is obtained atan address of RO₁ designated by a zoom code plate FCP. The data of theconversion factor kL is added to a conversion factor kC for theconverter lens COV outputted from the ROM RO₀, then the added data issent to the circuit in the body of the camera. Each of the data for kLand kC consists of a significant figure and an exponent part, the datain said each part are added respectively in the above addition in theconverter lens COV. Then the data are converted to the value kL indecimal system, and the calculation of kL×kB (wherein kB represents theconversion factor relating to the body of the camera) is performed toobtain the conversion factor k relating to the whole camera system inthe AF microcomputer MC₂.

The data fv of the focal length (which is manually set when theinterchangeable objective lens is a zoom lens, or fixed when theinterchangeable objective lens is a lens with a fixed focal length) isoutputted from the RO₁ which is transmitted to the converter lens COV,then the data fv is added to data fvc which is a change in the focallength fv caused by the mounting of the converter lens COV, and theadded data is outputted to the circuit in the body of the camera. Thedata dAv which is the difference between the effective aperture value atthe shortest focal length and the effective aperture value at the setfocal length (in case of a zoom lens) is outputted from the RO₁, whichis transmitted to the circuit in the converter lens COV, then the datadAv is added to the data dAvc which is the change in aperture value ofthe interchangeable objective lens caused by the use of the converterlens COV, and the added data is inputted to the circuit in the body ofthe camera. In the body of the camera, the value of Avo+dAv+dAvc is setas the effective fully open aperture value in the whole optical system,and the value of Avmax+dAv is set as the maximum effective aperturevalue. In case the converter lens COV is not arranged, dAvc=0. In case azoom lens which does not change the effective aperture value in zooming,dAv=0.

In the flow chart shown in FIG. 2, after the input operation of the lensdata is completed, at the step #4, it is determined whether the switchS₁ for measuring the brightness is closed or not. In case the switch S₁is closed, the program flow goes to step #6, on the other hand, in casethe switch S₁ is open, the program flow goes to step #5. At the step #5,it is determined whether the performing mode is an AF mode (automaticfocus control mode) or a FA mode (focus aid mode in which the focusadjustment is manually made with the aid of the focus detection signal)by detecting the input level to the terminal P₂₉. In case the performingmode is the FA mode, the program flow goes to the step #6, on the otherhand, in case it is the AF mode, the program flow goes to the step #12.The determination of the AF mode or the FA mode is performed by way ofthe following operation, that is, the FA mode is performed and AF modeis not performed when the switches TSS, ASS, ISS, MOSS, UPS and DOSexcept the switch S₁ for measuring the brightness of the object areclosed and the microcomputer for controlling MC₁ begins to be operated.

At the step #6, it is determined whether the check data is inputted fromthe circuit in the lens LE, in case the check data is not inputted, theoperation of the AF mode or the FA mode is not performed because thelens is not mounted, then the program flow goes to the step #12. In casethe check data is inputted, the program flow goes to the step #7, thenAFAvo or AFAvo+dAvc is compared with the effective aperture thresholdvalue for calculating the defocusing quantity for the AF mode or the FAmode, that is, it is determined whether the value of AFAvo or AFAvo+dAvcis more than the effective aperture threshold value such as Av=5 (incase of F5.6) or not. In case the value of AFAvo or AFAvo+dAvc is lessthan the effective aperture threshold value, the AF mode and the FA modeis not performed because it is impossible to measure the defocusingquantity, then the program flow goes to the step #12. The reason why thedata of the maximum F number (the effective aperture value at thelongest focal distance) is set as the value of AFAvo is as follows. Thatis, it is impossible to adjust and detect the focal distance because theeffective aperture value is more than the effective aperture thresholdvalue on the way that the focal distance is changed from the shortestfocal distance to the longest focal distance. Therefore, it is inhibitedto perform the AF mode and FA mode in order to prevent the operation ofthe camera from being stopping suddenly during the operation of the AFmode and the FA mode.

At the step #8, it is determined whether the level at the terminal P₂₀is "High" or "Low", that is, whether the operation of the AFmicrocomputer MC₂ is set about or not. In case the operation of the AFmicrocomputer MC₂ is set about, the program flow goes to the step #12.On the other hand, in case the operation has not been set about. Theterminal P₂₀ is made "Low" and the interrupt signal is inputted to theinterrupt terminal it₁ in the AF microcomputer MC₂, then the operationof the AF microcomputer MC₂ is set about. The operation of thesubroutine I is set about after a data request signal DTRQ is inputtedto the terminal P₂₆ from the AF microcomputer MC₂.

In the subroutine I, the required data is transferred to the AFmicrocomputer MC₂ in series in accordance with the said data requestsignal. First of all, the terminal P₂₅ is made "High" at the step #60,and the conversion factor kL is set in a resistor IOR used for the SIOoperation at the step #61, then the operation of the SIO is performed.Next, AFAvo and the data (80H) which means the presence of the converterlens COV is set in the resistor IOR, and the SIO operation is performed.Then it is determined whether or not a flag CDEF which designateswhether the calculation of the exposure control value has been completedhas been set, in case the flag CDEF is set, then the exposure controlvalue has been already calculated, a desired effective aperture valueAvc and a desired exposure time Tvc are set in the register IOR and theSIO operation is performed. On the other hand, in case the flag CDEF isreset, then the calculation of the exposure control time has notcompleted yet, AFAvo and Tv=6 (1/60 sec) is set in the register IOR, andthe SIO operation is performed. After the SIO operation is completed,the terminal P₂₅ is made "Low" and the program flow is returned.

At the step #12, the ISO data is set in accordance with the condition ofthe Sv switch ISS, the UP switch UPS and the DOWN switch DOS. Next, atthe step #20 it is determined whether the release switch S₂ is closed ornot. In case the release switch S₂ is closed, the operation of thesubroutine II as shown in FIG. 3 is performed, on the other hand, incase the release switch S₂ is open, at the step #21 the analog output ofthe measured brightness LMAN inputted from a light measuring circuit LMCshown in FIG. 1 is converted into a digital form in reference to areference voltage VRAN inputted from the reference voltage power sourcearranged in the light measuring circuit LMC to a reference voltage inputterminal VRI. At the step #22, it is determined whether the data requestsignal is inputted from the AF microcomputer MC₂ or not. In case thedata request signal is inputted, the operation of the subroutine I isperformed and the program flow goes to the step #24. On the other hand,the data request signal is not inputted, the program flow goes to step#24 directly.

At the step #24, each mode is set in accordance with the condition ofthe mode switch MOSS, the UP switch UPS and the DOWN switch DOS, theprogram flow goes forward in accordance with the content of the moderegister MOR. At the step #28 in case the content of the mode registerMOR is "0" which corresponds to the P mode, the calculation of the Pmode is performed at the step #29 and the program flow goes to the step#38. Next, the step #28, the content of the mode register MOR is "2"which corresponds to the A mode, at the step #33 the effective aperturevalue is set in accordance with the condition of the Av switch ASS, theUP switch UPS and the DOWN switch DOS, the program flow goes to the step#35 through the step #34, then the calculation of the exposure time isperformed, and the program flow goes to the step #38. Moreover, in casethe content of the mode register MOR is "3 which corresponds to the Smode, at the step #31 the exposure time is set in accordance with thecondition the Tv switch TSS, the UP switch UPS and the DOWN switch DOS,the program flow goes to the step #37 through the step #32, then thecalculation of the S mode is performed and the program flow goes to thestep #38. Finally, the content of the mode register MOR is "1" whichcorresponds to the M mode, the exposure time is set at the step #31 andthe effective aperture value is set at the step #33, then thecalculation of the M mode is performed at the step #36 and the programflow goes to the step #38.

At the steps #12, #31 and #33, the setting of the data Sv, Tvs and Avsare performed as follows. First of all, it is determined whether the Svswitch ISS, the Tv switch TSS, the Av switch ASS and the UP switch UPSor the DOWN switch DOS are closed or not. In case the UP switch UPS isclosed, 1/3 is added to the data Sv at the step #12, 1/2 is added to thedata Av at the step #31, 1 is added to the data Tv at the step #33. Incase the DOWN switch DOS is closed, 1/3 is subtracted from the data Svat the step #12, 1/2 is subtracted from the data Av at the step #31, 1is subtracted from the data Tv at the step #33. After that, it isdetermined whether each data is more than each predetermined thresholdvalue or not, only in case each data is more than the threshold value,the threshold value is set in each data. Moreover, the updating of eachdata is not performed after the setting of each data has been set oncewhen the UP switch UPS or the DOWN switch DOS has been closed. In casethe UP switch UPS or the DOWN switch DOS is closed again after theswitch is opened, the subsequent updating of the data is performed. Atthe step #24 when the mode is set, 1 is added to the content of theregister MOR after the mode switch MOSS and the UP switch UPS areclosed, then "0" is set in the content of the register MOR when thecarry is occurred, that is, the P mode→the M mode→the A mode→the S modeare set in turn. When the mode switch MOSS and the DOWN switch areclosed, 1 is subtracted from the content of the register MOR, "3 is setin the content of the register MOR when the borrow is occurred, that is,the P mode→the M mode→the A mode→the S mode are set in turn. Moreover,in case of changing the mode, changing the mode can be performed onlyafter the UP switch or the DOWN switch is opened once.

At the step #38, the flag CDEF is set since the calculation of theexposure control value is completed at the above steps, then it isdetermined whether the release switch is turned on or not. In case therelease switch is turned on, the program flow goes to the subroutine IIshown in FIG. 3, on the other hand, in case the release switch is turnedoff, the display data is outputted to the display unit DSP and theprogram flow goes to the step #42. In case of outputting the displaydata, the terminal P₂₇ is made "Low", the display data is set in theregister IOR, then the SIO operation is performed. At the step #42, itis determined whether the terminal P₃₇ is "Low" or not, in case theterminal P₃₇ is "Low", the program flow goes back to the step #2. On theother hand, in case the terminal P₃₇ is "High", when the UP switch UPSor the DOWN switch DOS is opened, therefore, the program flow goes tothe step # 43. Then it is determined whether the reset switch S₄ isturned on or not, in case the reset switch S₄ is turned on, (when theswitch S₄ is changed over to the terminal WE) it is determined whetherthe AF mode or FA mode is selected. Then in case the FA mode isselected, it become possible to the interrupt terminal it₀, the programflow goes back to the step #3. On the other hand, in case the AF mode isselected, the terminal P₂₁ is made "Low", an operation stop signal AFSTPof the AF microcomputer MC₂ is outputted to the AF microcomputer MC₂ atthe step #45, then the AF microcomputer MC₂ outputs an AF stop signalAFEN in accordance with the operation stop signal AFSTP. Upon inputtingthe signal AFEN, the terminals P₂₀ and P₂₁ are made "High", then it isdetermined whether the reset switch S₄ is turned on or not at the step#48. In case the reset switch S₄ is turned on, the program flow goesback to the step #3 through the step #49. That is, the above operationof reading, measuring the brightness of the object and calculation ofthe light measurement are performed in turn until the counterinterruption is enabled ever if the reset switch S₄ is turned on withall the switches TSS, ASS, ISS, MOSS, UPS, DOS and S₁ turned off and theterminal P₃₇ is "High". Then in case the FA mode is selected, theoperation of the AF microcomputer MC₂ can be performed continuously. Onthe other hand, in case the AF mode is selected, the operation of the AFmicrocomputer MC₂ stops when the terminal P₃₇ becomes "High".

When it is determined that the terminal P₃₇ is "High", in case the resetswitch S₄ is turned off, the operation of the AF microcomputer MC₂ stopseven though the AF mode or the FA mode is selected. Then the counterinterruption is inhibited at the step #51, it is permitted to interruptto the terminal it₀ at the step #52. Next, a permission signal STPOK ofstopping the operation of the AF microcomputer MC₂ is inputted at thestep #53, the flag CDEF is reset at the step #54, it is inhibited tooutput the reference clock pulses STCL at the step #55, the transistorBT₀ is turned off at the step #56, then the microcomputer MC₁ stops.

In the following, the counter interruption will described. As soon as apredetermined time (for example, five seconds) has passed after it isdetermined that the terminal P₃₇ is "High" and the reset switch S₄ isturned on, the counter interruption is performed from the step #120.First of all, it is determined whether the FA mode or the AF mode hasbeen selected. In case the FA mode is selected, when the operation ofthe AF microcomputer MC₂ has been performed continuously, the AFmicrocomputer MC₂ is stopped, and the program flow goes to the step#124. On the other hand, in case the AF mode is selected, when theoperation of the AF microcomputer MC₂ has been already stopped, theprogram flow goes to the step #124. Moreover, the counter interruptionis inhibited and it is permitted to interrupt to the interrupt terminalit₀. After the permission signal STPOK of stopping the operation of theAF microcomputer MC₂ is inputted at the step #126, the reference clockpulses STCL are stopped at the step #127 and the transistor BT₀ isturned off. Then the flag CDEF is reset at the step #129 and theoperation is made to stop.

In the following, the operation of the subroutine II will be described.At the step #80, it is determined whether the flag CDEF has been set ornot, in case the flag CDEF has been reset, when the calculation of theexposure control value has not been completed, the program flow goesback to the main routine. In case the flag CDEF has been set and thecalculation of the exposure control value has been completed, theprogram flow goes to the step #81. Then a signal INREL which designatesthat the operation of controlling the exposure has been performed isoutputted. After the signal AFEN is inputted at the step #82, theprogram flow goes to the operation of the exposure control. Table 4shows the correlation between the outputs of the terminals P₄₁, P₄₂ andP₄₃, the output of a driver DEDR, the magnet in operation and theoperation of the camera.

                  TABLE 4    ______________________________________    P.sub.41         P.sub.42                P.sub.43                       X.sub.1                           X.sub.2                               X.sub.3                                   X.sub.4                                       X.sub.5                                           Magnet Operation    ______________________________________    L    H      H      H   L   L   L   L   RELC   release    H    L      H      L   H   L   L   L   APSC   interrupt                                                  stopping                                                  down opera-                                                  tion    L    L      H      L   L   H   L   L   MRC    mirror up    H    H      L      L   L   L   H   L   1CC    first curtain                                                  start    L    H      L      L   L   L   L   H   2CC    second                                                  curtain start    H    H      H      L   L   L   L   L   *      operation dis-                                                  able    ______________________________________

In the operation of controlling the exposure, first of all, theoperation of the stopping down of the aperture is set about after theoperation of releasing, the time T₀ is counted. The pulses of a pulsegenerating device APC are inputted to an event counter APCO through aterminal CLI₁, the step data AVc-Avo for stopping down of the aperture,which are preset in the counter, are subtracted by one each time saidpulse from the pulse generating device APC is inputted. When the contentof the counter APCO become "0", the interruption is enable to stop thestopping down of the aperture at the step #88, then the program flowgoes back to the subroutine II. On the other hand, in the subroutine II,the mirror is raised after the operation of counting the time T₀ iscompleted, then the time T₁ is counted. The operation of stopping downof the aperture is stopped during the time period T₀ +T₁. After the timeT₁ has passed, the mirror is completely raised, the first curtain beginsto run at the step #91. After the time 2^(-Tvc) has passed, the secondcurtain begins to run at the step #94. When the reset switch S₄ isturned off, the signal INREL representing the period of controlling theexposure is eliminated with the flag CDEF reset and the program flowgoes back to the step #42 in the main routine.

In FIG. 1, MLMC denotes a CCD comprising at least two pairs of the lightreceiving unit which receive the light passed through the photographiclens and distributed by a known optical distribution system. Theinterface circuit INF outputs "High" pulse to the terminal φR for makingthe charge storing unit in the CCD at a predetermined voltage. When thesaid pulse becomes "Low", storing the charge in accordance with thereceived light quantity in the light receiving component of the chargestoring unit is set about. In the interface circuit INF, a monitoroutput AMO outputted from the light receiving quantity monitor unit ofthe CCD is compared with the reference level, the transfer pulse isoutputted to the terminal φT as soon as the monitor level reaches thereference level. In the CCD, the charge stored in the charge storingunit is transferred to the transfer gate (an analog shift register), asignal ANO of the stored charge which corresponds to the received lightquantity in each light receiving unit is outputted in turn in accordancewith the pulse used for transferring from the terminals φ₁, φ₂ in theinterface circuit INF. When storing the charge is completed and theinterface circuit INF outputs the transfer pulse to the terminal φT, theinterface circuit INF outputs a signal INEN which designates that theoperation of storing the charge is completed to the AF microcomputerMC₂.

The interface circuit INF converts an analog signal ANO inputted to adigital signal, and outputs a "Low" pulse signal ADEN, which designatesa timing used for inputting the converted data to the AF microcomputerMC₂, whenever the said A-D conversion is completed. Then the interfacecircuit INF outputs the A-D converted data to the input port D₀ in theAF microcomputer MC₂ through a bus ADD. When the storing time has passedbeyond a predetermined time and the monitor output AMO is less than thereference level, the AF microcomputer MC₂ outputs a "Low" pulse INSTPfor stopping the operation of storing the charge in the CCD compulsorilyand make the operation of storing the charge compulsorily. After that,in accordance with the above stop of the operation of storing thecharge, the interface circuit INF amplifies the input signal ANO inaccordance with the monitor level AMO at that time when the operation ofstoring the charge is made to stop, and A-D convert the said amplifiedsignal to a digital signal. Then the interface circuit INF transfers theA-D converted signal to the AF microcomputer MC₂.

MCC denotes a control circuit for the motor MO. First of all, therotation of the motor MO is transferred to a driving member in theconverter lens COV through a transferring member not shown.

Said rotation of the motor MO is transferred to a driven member in theinterchangeable objective lens LE through a transferring member in theconverter lens COV and focusing is performed in the optical system ofthe interchangeable objective lens LE. Moreover, the rotation of themotor is transferred to an encoder ENCC, which produces pulsesrepresenting the rotation of the motor MO (referred to as rotationpulse) in accordance with the rotation of the motor. The rotation pulsesare inputted to an event counter in the AF microcomputer MC₂ through theterminal CLI₀. Said event counter is set by the data of a predeterminedand required rotation number of the motor MO. The data in the eventcounter is subtracted in accordance with the pulse. When the opticalsystem for focusing in the interchangeable objective lens is moved bysaid predetermined length, the content of the event counter becomes "0",the interruption from the event counter is performed and the rotation ofthe motor MO is made to stop or to be changed from high speed to the lowspeed. The motor control circuit MCC makes the motor MO rotate in aclockwise direction when the terminal P₄ in the AF microcomputer MC₂ is"Low" and makes the motor MO rotate in a counterclockwise direction whenthe terminal P₅ in the AF microcomputer MC₂ is "Low". On the other hand,the motor control circuit MCC stops the motor MO when the both terminalsP₄ and P₅ is "High". Moreover, the motor MO is controlled to rotate atthe high speed when the terminal P₆ in the AF microcomputer MC₂ is"High", on the other hand, the motor MO is controlled to rotate at thelow speed when the terminal P₆ is "Low".

A light emitting diode RFL is used for displaying the condition that theimage of the object is out of focus backward, a light emitting diode IFLis used for displaying the condition that the image of the object is infocus, and a light emitting diode FFL is used for displaying thecondition that the image of the object is out of focus forward. Theabove three light emitting diodes are selectively turned on by the "Low"state of the terminals P₇, P₈ and P₉.

FLS denotes a switch used for locking the lens in the focused condition,when the switch FLS is closed, the motor MO is made to stop and theoptical system for photographing is fixed at the position that the imageof the object is in focus. When a switch AMS is changed over to theterminal AF, the AF mode is selected. On the other hand, when the switchAMS is changed over to the terminal FA, the FA mode for only displayingthe in focus condition is selected. A switch SNS is switched to theterminal SIN during the single mode in which the AF microcomputer MC₂ isoperated by itself such as the following mode. That is, for example, thesingle mode is the operation mode of the AF microcomputer MC₂ when theinterchangeable objective lens with the circuit used for controlling thefocal distance automatically is set as an AF lens, when the circuit usedfor controlling the focal distance automatically is set in a camera witha fixed lens for taking picture which can not be changed, or when theoperation of the AF microcomputer MC₂ is checked. On the other hand,when the circuit arrangement used for automatic focus controlling ismounted in the body of the camera with the interchangeable objectivelens, the switch SNS is switched to the AF microcomputer MC₂ through aterminal NOM, then the AF microcomputer MC₂ operates in the normal mode.Moreover, the both operating program of the single mode and the normalmode are stored in the AF microcomputer MC₂, one of the two program isused in accordance with the condition of the switch SNS. The switch SNSis set on or off in the production process of the camera system. Theswitch SNS is so arranged in the camera that only particular operatorscan access it.

FIG. 5 shows an example of a circuit arrangement in which an AF controlcircuit such as the AF microcomputer MC₂ is mounted in theinterchangeable lens. In this case, the switch is connected to theterminal SIN. Moreover, the data of the predetermined conversion factorof the lens is inputted to the terminals P₇, P₉ ˜P₁₁ and P₁₃ ˜P₁₆. Thatis, the data outputted from a zoom code plate FCP in accordance with theset focal distance is converted to the data of the conversion factorthrough a decoder DCC, the data of the conversion factor is inputted tothe above terminals P₇, P₉ ˜P₁₁ and P₁₃ ˜P₁₆. Moreover, as the displaydevice used for displaying the in focus condition, a buzzer BZcontrolled by a control circuit SOC is employed without any emittingdiode therefore. The operation of the AF microcomputer MC₂ is set aboutas soon as the driving power is supplied. Therefore, it is not necessaryto provide a function of the said interrupt terminal it₁, the AFmicrocomputer MC₂ is connected to the driving power line through thepull up resistor. As the AF operation is stopped when the driving poweris cut off, or when the exposure control operation of the camera is setabout, it is not necessary to provide the said interrupt terminal it₂and the AF microcomputer MC₂ is connected to the driving power directly.In the above description, it is not necessary to read the serial dataafter the data of the lens LE is transferred to the AF microcomputer MC₂through the microcomputer MC₁, therefore, a serial input terminal SIIN₀and the clock input terminal SICK₀ are connected to the driving powerline directly.

Referring to the flow charts shown in FIGS. 6 and 11, the operation ofthe AF microcomputer MC₂ will be described. The operation of the AFmicrocomputer MC₂ is set about from the step No. 1 as soon as the powerswitch is turned on. At the step No. 1, all the flags are reset. In caseeach flag is set "0" at the initial condition, it is easy to initializeall the flags. At the step No. 2, all the output data (the dark outputof the CCD) on the condition that the light is projected to the CCD areset "0". Next, at the step No. 3, the signal outputted from the switchSNS used for switching the single mode or normal mode is read. In casethe said signal is "High", this case corresponds to the lens single bodymode (the single mode), the program flow goes to the step No. 9. Thenthe input and output ports used in the single mode are initialized atthe steps No. 9 and No. 10. However, in this case it is enough that theports used only as the output mode are initialized at the steps No. 9and No. 10, because all the input and output ports are set as the inputmode at the power on reset performed when the above power switch isturned on. Then at the step No. 11 and No. 12, it is permitted tointerrupt to only the terminal it₃, the program flow goes to the stepNo. 36 which is the head step of the storing routine. In case of thesingle mode, the operation of the said single mode is set about byturning the power switch on. In case of the focusing mode only one shotAF control mode (the position of the lens is fixed after the AF controlis once perfected) is performed. On the other hand, at the step No. 3,in case it is determined that the terminal P₁₂ to which the signaloutputted from the switch SNS is inputted is "Low". This casecorresponds to the camera mode (normal mode), at the steps No. 4, No. 5and No. 6, the input and output ports are initialized. Then at the stepsNo. 7 and No. 8, it is permitted to interrupt to the terminals it₁, it₂and it₃ and the program flow goes to the operation of the stop mode. Thestop mode is one of functions provided in the microcomputer, which is apower saving mode with the clock pulses stopped holding the content ofthe memory unchanged. Using the power saving mode prevents fromconsuming the unnecessary power. In the operation of the AFmicrocomputer MC₂, the program flow goes out from the stop mode byperforming the reset or inputting any interrupt signal. Moreover, thefollowing is not shown in the flow charts, the microcomputer MC₁ canperform the power on reset operation like the AF microcomputer MC₂. Whenthe power on reset operation is made to stop, the microcomputer MC₁outputs the signal AFSTP in order to stop the AF operation. As soon asthe AF microcomputer MC₂ receives the signal AFSTP, it is determinedwhether it is permitted or not that the operation of the AFmicrocomputer MC₂ is made to stop. In case it is permitted, the AFmicrocomputer MC₂ outputs the "Low" signal STPOK which represents thatit is permitted that the operation of the AF microcomputer MC₂ is madeto stop. Then the microcomputer MC₁ stops to output the reference clockpulses STCL and the operation of the both microcomputers MC₁ and MC₂ ismade to stop.

In case of the normal mode, when the AF microcomputer MC₂ sets about,the AF microcomputer MC₂ outputs a "Low" signal AFSTA. Then theinterrupt signal inputs to the interrupt terminal it₁, the program flowgoes to the step No. 14. At the step No. 14, the terminal P₁₃ is made"High" and it is informed to the microcomputer MC₁ that the referenceclock pulses must be continued, and in turn at the step No. 15, theterminal P₁₄ is made "Low", it is informed to the microcomputer MC₁ thatthe operation of the AF microcomputer MC₂ sets about. At the step No. 16through No. 20, it is permitted to interrupt to the interrupt terminalit₂ and it₃ only in case of a necessary interruption, on the other hand,an unnecessary interruption is inhibited. At the step No. 21, thecondition of the after a release flag AFRF which designates whether therelease operation has been operated is detected, then it is determinedwhether or not the interruption to the interrupt terminal it₁ wasperformed after the release operation. In case the flag AFRF is "1", theprogram flow goes to the step No. 22 with the interruption performedafter the release operation. The operation from the step No. 21 will bedescribed later. In case the flag AFRF is "0" at the step No. 21, theprogram flow goes to the step No. 27. The operation from the step No. 27is an operation of a first serial communication that the data aretransferred in series between the microcomputer MC₁ and the AFmicrocomputer MC₂. At the step No. 27, "0" is set in the serial datacounter k, wherein the data has four data and the length of each data iseight bits. Next, the interruption in the serial communication ispermitted. When the interruption in the serial communication isperformed, eight pulses of the serial clock pulses SICK are inputted tothe terminal SICK₀. After the eight pulses of the serial clock pulsesSICK are inputted to the serial data register, the interruption isperformed. At the step No. 30, the terminal P₁₆ is made "Low" and thedemand signal DTRQ in the serial communication is outputted to themicrocomputer MC₁. After the microcomputer MC₁ receives the demandsignal DTRQ, the microcomputer MC₁ outputs the serial clock pulses andthe data, then the microcomputer MC₁ makes the terminal P₂₅ "High".Making the terminal P₂₅ "High" is performed in order to prevent the datapassing through the serial communication line from interfering. The said"High" signal is used for selecting each circuit because the serialcommunication line is used for communicating with the display unit DSP,the ROM in the lens LE and so on. When the microcomputer MC₁communicates with the AF microcomputer MC₂ in series, the microcomputerMC₁ makes the terminal P₂₅ "High", then the serial communication linecan be used to communicate with the AF microcomputer MC₂. When theselecting signal CSAF is "Low", the AF microcomputer MC₂ closes the gateof the serial clock pulses SICK. On the other hand, when the selectingsignal CSAF is "High", the AF microcomputer MC₂ opens the gate for theserial clock pulses SICK. Therefore, the selecting signal CSAF preventsthe AF microcomputer MC₂ from sending and receiving from and to theother circuit.

After the microcomputer MC₁ outputs the signal DTRQ in order to performthe serial communication, the microcomputer MC₁ waits until all the dataare inputted by the interruption at the step No. 31. After the eightpulses of the serial clock pulses SICK are inputted, the interruption isperformed. Then the program flow goes to the step No. 225 shown in FIG.6. The data inputted to the serial register are transferred to aregister SDR_(k) at the step No. 225, and the next register SDR_(k+1) isset at the step No. 226. At the step No. 227, the microcomputer MC₁outputs a "High" signal to the terminal DTRQ and the program flow goesto the step No. 31 in FIG. 7. After the interruption has been performedfour times, with all the data inputted, the content of the serial datacounter is "4". Then the program flow goes to the step No. 32 throughNo. 31, then the serial interruption is inhibited and the serialcommunication is completed. At the step No. 33, it is determined whetherthe signal inputted from the switch AMS used for selecting the AF modeor the FA mode to the terminal P₁₁ is "High" or not. In case the signalis "High", when the AF mode has been selected, a focus mode flag FMF ismade "0". On the other hand, in case the signal is "Low", when the FAmode has been selected, "1" is set in the flag FMF. Then the programflow goes to the integral routine from the step No. 36. In case of thesingle mode, the program flow goes from the step No. 12 to the step No.36 because it is not necessary to perform the serial communication.

At the step No. 36, a low light flag LLF is reset. The flag LLF is setwhen the charging time of the CCD has passed for a predetermined maximumtime in case of an object with low brightness. At the step No. 37, thecontent of the event counter is set in a register n₁. The event counteris a subtraction counter which subtracts "1" each time during which thenegative edge of the pulses are inputted to the terminal CLI₀. Thepulses inputted from the encoder circuit ENCC detecting the rotationquantity of the motor MO are inputted to the said terminal CLI₀. Thecontent of the event counter (the content of the register n₁) is usedfor the correction of the amount of the movement of the lens when thedefocus quantity is being measured during driving the motor MO, thecontent of the event counter is not used when the motor MO is notrotating. At the step No. 38, a timer is reset, and the interruption ofthe timer is permitted at the step No. 39. At the step No. 40, the "Low"signal is outputted to the line terminal P₁ for a predetermined time andthereby the interface circuit INF is made to set about the integraloperation of the CCD. At the step No. 41, the timer starts and count theintegral time. At the step No. 42, it is determined whether the integralcompletion signal is inputted from the interface circuit INF or not. Thesignal INEN becomes "Low" when the charging quantity of the CCD reachesa predetermined proper value, the "Low" signal INEN represents thecompletion of the interruption of charge in the CCD. After the signalINEN is detected "Low", when charging is completed, the program flowgoes to the step No. 49 through No. 48. In case the signal INEN is"High", it is detected whether the counting time of the timer reaches atime t₁ or not. The time t₁ corresponds to the time interval at which itis detected that the lens is moved to the end position. In case anypulse from the encoder circuit is not inputted, it is determined thatthe lens has been moved to the end position. In order to perform thedetermination, at the step No. 45, the subroutine shown in FIG. 11 whereit is detected that the lens has been moved to the end position isexecuted. At the step No. 43, in case the timer value is not equal tothe time t₁, the program flow goes to the step No. 44, then it isdetermined whether the timer value reaches the maximum integral time t₂or not. In case the timer value reaches the time t₂, the program flowgoes to the step No. 46. In case the timer value does not reach the timet₂ , the program flow goes back to the step No. 42, then the aboveoperation is repeated. When the integral operation of the CCD iscompleted until the timer value becomes a time t₀ (t₀ <t₂), the objecthas high brightness, then a flag HLF is set. On the other hand, in casethe brightness of the object is low, the flag HLF is reset and theprogram flow goes to the step No. 49.

When the charging time reaches the maximum charging time, a "Low" signalis outputted to the terminal P₂ at a predetermined time and the integraloperation is stopped compulsorily. At the step No. 47, the low lightflag LLF is set and the high light flag HLF is reset, the program flowgoes to the step No. 49. The timer interruption is inhibited at the stepNo. 49, the timer is made to stop at the step No. 50. At the step No.51, the content of the event counter is set in a register n₂ in the sameway as made in the step No. 37. A digital value converted from theoutput of the CCD in the interface circuit is inputted as a signal ADDevery predetermined interval since the integral operation is completed.At the step No. 52, the said signal ADD is inputted to the input port D₀at the negative edge of the timing signal ADEN inputted to the terminalP₃ and the signal ADD is stored in a memory.

After input of the data is completed, the terminal P₁₂ is checked, andin case the terminal P₁₂ is "Low", under the normal mode, the programflow goes to the step No. 54. On the other hand, in case the terminalP₁₂ is "High", under the single mode, the program flow goes to the stepNo. 55. At the step No. 54, the value subtracted the data of the darkoutput from the respective output data of the CCD is set as the data forcompensation of the dark output.

At the step No. 55, the subroutine of the focus lock check shown in FIG.6 is called. The subroutine of the focus lock check sets about from thestep No. 229. At the step No. 229, the flag FMF is checked. In case theflag FMF is "1", under the FA mode, the program flow returns withoutchecking the focus lock switch FLS. On the other hand, in case the flagFMF is not "1", under the AF mode, the program flow goes to the step No.230, then the signal inputted from the focus lock switch FLS is checked.In case the signal inputted from the focus lock switch FLS is "High",when this case does not mean the condition of the focus lock, theprogram flow goes to the step No. 236. On the other hand, in case thesignal inputted from the focus lock switch FLS is "Low", when this casemeans the condition of the focus lock, the program flow goes to the stepNo. 231. At the step No. 231, a focus lock flag FLF is checked, in casethe flag FLF is "1", the program flow returns. In case the flag FLF is"0", the program flow goes to the step No. 232, then the stop signal isoutputted to the motor MO. Next, a motor flag MOF is reset. Then thecounter interruption is inhibited, and the flag FLF of the focus lock isset. After that, the program flow returns to the step No. 36. Moreover,at the step No. 230, in case the signal inputted from the focus lockswitch FLS is "High", the focus lock flag FLF is checked at the step No.236. In case the flag FLF is "0", the program flow returns determiningthat the previous routine already executed is not the focus lock. On theother hand, in case the flag FLF is "1", the focus lock flag FLF isreset at the step No. 237 due to the condition that the focus lock isalready released. Next, it is determined whether a low contrast flagLCF₀ is "1" or not. When the low contrast flag is "1", this case meansthe condition that the contrast of the image is low. In case the flagLCF₀ is "1", all the low contrast flags LCF₀, LCF₁, LCF₂ and LCF₃ arereset and initialized, and the display is turned off at the step No.240, then the program flow returns to the step No. 36. On the otherhand, in case the flag LCF₀ is not "1" at the step No. 238, the programflow goes to the step No. 240 without performing the step No. 239, thenthe display is turned off at the step No. 240 and the program flowreturns to the step No. 36.

The program flow goes back to the step No. 57 of the main routine, thepreparation of the serial communication will be performed again. Theoperation of the steps No. 57 through No. 59 is the same operation asthe operation of the steps No. 27 through No. 30. The serialcommunication is performed in order to input various data. The operationof the serial communication is performed by interrupting during thecalculation at the step No. 60. On the other hand, in case the terminalP₁₂ is "High", under the single mode, the program flow goes to the stepNo. 55. Then the conversion data are inputted from the decoder circuitDCC shown in FIG. 5 to the terminals P₇, P₉ ˜P₁₁ and P₁₃ ˜P₁₆, and thedata is stored in a memory. The program flow goes to the step No. 60. Atthe step No. 60, the predetermined calculation is performed inaccordance with the data inputted from the CCD, wherein a defocusingquantity Δε and a defocusing direction are calculated. At the step No.61, the serial interruption is inhibited, the program flow goes to thestep No. 62 wherein the contrast determination is performed. In thecontrast determination, it is determined whether the brightness of theimage can be detected in accordance with the output of the CCD or not.

At the step No. 62, in case it is determined that the image has a lowcontrast, the program flow goes to the step No. 63. On the other hand,in case it is determined that the image has the normal contrast, theprogram flow goes to the step No. 93. Next, at the step No. 63, it isdetermined whether the flag FLF representing the condition of the focuslock is "1" or not. In case the flag FLF is "1", the program flow goesto the step No. 82. At the steps No. 82 through No. 85, displaying thecondition of the low contrast (turning the light emitting diodes RFL andLFL on and off continuously) and setting of the low contrast flag LCF₀is performed. Then the program flow goes to the step No. 36 in order tomeasure again. On the other hand, in case the flag FLF is not "1", whenthis case does not mean the condition of the focus lock, the programflow goes to the step No. 64. In case the flag FMF is "1 ", when the FAmode has been selected, the program flow goes to the step No. 82. On theother hand, In case the flag FMF is not "1", when the AF mode has beenselected, the program flow goes to the step No. 65, then it isdetermined whether the motor MO is rotating or not.

In case the motor MO stops, the program flow goes to the step No. 66,then it is determined by the low contrast flag LCF₃ (the flag isreferred to as a scan inhibit flag of the low contrast) whether scanningwith the low contrast can be performed or not. In case the flag LCF₃ is"1", when scanning is inhibited, the program flow goes to the step No.82. On the other hand, in case the flag LCF₃ is not "1", when scanningwith the low contrast is permitted, the program flow goes to the stepNo. 67. In the steps No. 67 through No. 69, displaying the condition ofthe low contrast and setting the low contrast flag LCF₀ are performed.Next, at the step No. 70, the low contrast flag LCF₁ (the scan flag ofthe low contrast) is set. At the step 71, it is determined by the lowlight flag LLF whether the object has low brightness or not. In case theflag LLF is "1", when the object has low brightness, the low contrastflag LCF₂ which is the inverse of the scan flag is set at the step No.73, then the program flow goes to the step No. 76. In case of the objectwith low brightness, the above operation is performed in order toperform scanning with the low contrast only in such a direction as thelens moves to the body of the camera and in order that the lens may moveinto the ∞ position when the lens cap is mounted. In case the flag LLFis not "1", when the object has not low brightness, the program flowgoes to the step No. 72, then the low contrast flag LCF₂ is reset. Atthe step No. 74, in case of the rear defocusing, that is, when the imageis out of focus backward, a driving direction flag DDF is reset at thestep No. 75. On the other hand, at the step No. 74, in case of the frontdefocusing, that is, when the image is out of focus forward, the drivingflag DDF is set at the step No. 76, then the program flow goes to thestep No. 77. At the step No. 77, "High" is outputted to the terminalP₁₆, the rotation speed of the the motor MO is set in a high speed mode.The motor flag MOF is set at the step No. 78, then at the step No. 79,the driving power is supplied to the motor MO with the polaritycorresponding to the driving direction flag DDF. Then scanning isperformed and the program flow goes back to the step No. 36.

At the step No. 65, in case it is determined that the motor MO isrotating, it is determined whether the flag LCF₁ is "1" or not at thestep No. 86. That is, it is determined whether the motor MO is rotatingby scanning with the low contrast or by driving on the normal condition.In case the flag LCF is "1", when the motor MO is rotating by scanningwith the low contrast, detecting whether the lens is at the end positionor not is performed. Then the program flow goes back to the step No. 36and scanning with the low contrast is set about continually. On theother hand, at the step No. 86, in case the flag LCF₁ is not "1", whenthe motor MO is rotating by driving on the normal condition, the programflow goes to the step No. 87. First of all, the motor is made to stopand the motor flag MOF is reset. Then the low contrast flag LCF₀ is set,the condition of the low contrast is displayed and the program flow goesback to the step No. 36 in order to measure again.

At the step No. 62, it is determined that the object has not lowcontrast, the program flow goes to the step No. 93. At the step No. 93,it is determined whether the flag FMF is "1" or not. In case the flag is"1", when the FA mode has been selected, the program flow goes to thestep No. 97. At the step No. 97, the low contrast flag LCF₀ is checked.In case the low contrast flag LCF₀ is "1", when the object has lowcontrast, the low contrast flag LCF₀ is reset at the step No. 98, thedisplay of the condition of the low contrast is turned off, then theprogram flow goes to the step No. 106. On the other hand, in case theflag FMF is not "1", under the AF mode, the program flow goes to thestep No. 94. At the step No. 94, the scan inhibit flag LCF₃ of the lowcontrast is set. Therefore, scanning under the low contrast is inhibitedso far as the object has the normal contrast once. At the step No. 95,it is determined by the low contrast flag LCF₀ whether the object hashad the low contrast up to now or not. In case the flag LCF₀ is "1",when the object has had the low contrast, the program flow goes to thestep No. 101. At the step No. 101, the driving power stops to besupplied to the motor MO. Next, the motor flag MOF is reset at the stepNo. 102, the low contrast flags LCF₀, LCF₁ and LCF₂ are reset. Then itis determined whether the terminal P₁₂ is "High" or not at the step No.104. In case the terminal P₁₂ is not "High", when the normal mode hasbeen selected, the display of the condition of the low contrast isturned off and the program flow goes back to the step No. 36 in order tomeasure again. On the other hand, at the step No. 104, in case theterminal P₁₂ is "High", the program flow goes back to the step No. 36directly.

At the step No. 95, in case the flag LCF₀ is not "1", when the objecthas not had the low contrast, the program flow goes to the step No. 96.Then the focus lock flag FLF is checked, in case the flag FLF is not"1", when this case is not the condition of the focus lock, the programflow goes to the step No. 121. On the other hand, in case the flag FLFis "1", when this case is the condition of the focus lock, the programflow goes to the routine of the FA mode performed from the step No. 106.At the step No. 106, a focus width ZFA in the FA mode is set. The focuswidth ZFA in the FA mode varies in accordance with the maximum F numberAFAv₀ used for controlling the focal distance automatically. In thepresent embodiment, ZFA is set as (AFAv₀ +α)×β, wherein α is a biasvalue, β is an appropriate factor and ZFA has the unit μm. Next, theprogram flow goes to the step No. 108, it is determined whether thedefocusing quantity Δε is within the range of the focus width ZFA ornot. In case the defocusing quantity Δε is within the range of the focuswidth ZFA, the program flow goes to the step No. 119. On the other hand,in case the defocusing quantity Δε is not within the range of the focuswidth ZFA, the program flow goes to the step No. 111.

In the following, the operation on the condition that the defocusingquantity Δε is within the range of the focus width ZFA will bedescribed. First of all, at the step No. 119, the AF microcomputer MC₂outputs a "High" signal to the terminal P₁₄ in order to inform it to themicrocomputer MC₁ that the image of the object has been in focus. Next,at the step No. 120, the light emitting diode IFL representing that theimage of the object is in focus is turned on, and the program flow goesback to the step No. 36 in order to measure the light again. In theroutine from the step No. 111, the operation on the condition that thedefocusing quantity Δε is not within the range of the focus width ZFA isperformed. At the step No. 111, the AF microcomputer MC₂ outputs a "Low"signal to the terminal P₁₄ in order to inform it to the microcomputerMC₁ that the image of the object is out of focus. Then the AFmicrocomputer MC₂ outputs a "High" signal to the terminal P₈ and thedisplay of the in focus condition is turned off. At the step No. 113, itis determined whether the flag FMF is "1" or not. In case the flag FMFis not "1", when the AF mode has been selected, the program flow goes tothe step No. 115. In case of the AF mode, the program flow comes to thisroutine only on the condition of the focus lock. Then the display of thedefocus is turned off and the program flow goes back to the step No. 36in order to measure again. In case of the FA mode, when the program flowcomes to the step No. 114, the defocusing direction is determined. Incase the image of the object is out of focus backward, the lightemitting diode RFL is turned on at the step No. 116. On the other hand,in case the image of the object is out of focus forward, the lightemitting diode FFL is turned on at the step No. 117, then the programflow goes back to the step No. 36 in order to measure again.

After the program flow comes from the step No. 96 to the step No. 121shown in FIG. 9, it is determined whether the converter lens COV ismounted or not. The mounting information of the converter lens COV istransferred from the microcomputer MC₁ by the serial communication atthe step 31 shown in FIG. 7. In case the converter lens COV has not beenmounted, it is determined whether the conversion factor kL is less thanthe threshold level K₁ or not at the step No. 122. The threshold levelK₁ is the conversion factor at the threshold level that it becomesdifficult for the motor MO to stop within the range of a minimum value bof the focus width when the preciseness of stopping the motor MO istaken account into. At the step No. 122, in case it is determined thatthe conversion factor kL is more than or equal to the threshold levelK₁, the minimum value b is set as the focus width ZFA in the AF mode atthe step No. 124, then the program flow goes to the step No. 126. At thestep No. 122, in case the conversion factor kL is less than thethreshold level K₁, Av×a, that is, the value multiplied the effectiveaperture value Av during taking a picture by a value "a" is set as thefocus width ZFA, wherein the value "a" is predetermined so that thevalue of ZFA is more than the minimum value b, that is, the image of theobject may be in focus within the range of the position at which thelens moves freely. Therefore, widening the focus width is to make themotor MO rotate smoothly at the range at which it is difficult tocontrol the rotation of the motor MO. At the step No. 121, in case it isdetermined that the converter lens COV is mounted, the program flow goesto the step No. 125. (Av+C)×a, that is, the value multiplied the value,which is made by which the effective aperture value Av is added to abias value C, by a factor "a", is set as the focus width ZFA. Adding thebias value C prevents it from being more difficult to control the motorMO when the converter lens COV is mounted than the case "ZAF=Av×a" ofthe step No. 123.

After setting of the focal width is completed, the defocusing quantityand the focus width are respectively converted to pulse count values forthe encoder ENCC at the step No. 126. That is, the converted value Δ_(n)', which is the pulse count value of the defocusing quantity, is made bymultiplying the defocusing quantity Δε by the value multiplied theconversion factor kL in the lens by the conversion factor kB in the bodyof the camera. Similarly, a converted value ZAFC, which is the pulsecount value of the focus width ZFA, is made by multiplying the focuswidth ZFA by the value multiplied by the conversion factor kL in thelens by the conversion factor kB in the body of the camera. Moreover, itis necessary for the data kL to convert to the conversion factor adecimal system, because the conversion factor transferred from themicrocomputer MC₁ is the data kL which consists of the fractional partand the exponential part.

At the step No. 127, it is determined by the motor flag MOF whether themotor MO is rotating or not. In case the motor flag MOF is not "1", whenthe motor MO stops, a count value Δn' of the defocus pulses is set as anumber of driving pulses at the step No. 128, then the program flow goesto the step No. 135. On the other hand, at the step No. 127, the motorflag MOF is "1", when the motor MO is rotating, it is determined whetherthe lens is at the end position. In case the lens is not at the endposition, the count value of the encoder is read into the register n₃ assoon as the operation at the step No. 131 is completed. The compensationquantity Δn"=n₁ -n₃ -(n₁ -n₂)/2 by moving is calculated at the step No.133, and the compensation defocus count value Δn=Δn'-Δn" is calculatedin order to compensate the moved quantity of the lens at the step No.134. Then, at the step No. 135, it is determined whether the defocuscount value Δn is within the range of the count value of a focus widthZFAC or not. In case Δn is more than ZAFC, the program flow goes to thestep No. 149. In case Δn is less than or equal to ZAFC, when the imageof the object is in focus, the program flow goes to the step No. 136. Atthe step No. 136, the driving power stops to be supplied to the motorMO, then the motor flag MOF is reset at the step No. 137. Next, at thestep No. 138, the compensation defocus count value Δn is set as theformer defocus quantity ΔnL. Then the program flow goes to the step No.139, it is determined whether the terminal P₁₂ is "High" or not. In casethe terminal P₁₂ is "High", when the single mode has been selected, theprogram flow goes to the step No. 145. The AF microcomputer MC₂ outputs"Low" to the terminal P₈ at the step No. 145, the buzzer informing thein focus condition vibrates at a predetermined time at the steps No. 146and No. 147. In case of the single mode, one measuring operation iscompleted. Then the AF microcomputer MC₂ waits the interrupt signal atthe step No. 148.

At the step No. 139, in case the terminal P₁₂ is "Low", under the singlemode, then an in focus flag AFIFF is set at the step No. 140 and a firstout flag FOF is reset. Then the AF microcomputer MC₂ outputs "High" tothe terminal P₁₄ in order to inform it to the microcomputer MC₁ that theimage of the object has been in focus. Then the AF microcomputer MC₂outputs "High" to the terminals P₇ and P₉ and output "Low" to theterminal P₈ in order to turn the light emitting diode IFL on. Theprogram flow goes back to the step No. 36 in order to measure again.

Moreover, at the step No. 135, in case it is determined that Δ is morethan ZAFC, the AF microcomputer MC₂ outputs "Low" to the terminal P₁₄ inorder to inform it to the microcomputer MC₁ that the image of the objectis still out of focus. Next, at the step No. 150, in case it isdetermined that the motor flag MOF is "1", the program flow goes to thestep No. 155, then n₃ is set as the former defocus count value ΔnL. Onthe other hand, in case the motor flag MOF is not "1", when the motor MOstops, the program flow goes to the step No. 151. In the following,setting of the near zone near the focus will be described. First of all,there is provided two kinds of width of the near zone, that is, one iswidth Nzn used for determining whether the lens has been in the nearzone when the lens is moved from the outside of the near zone into theinside of the near zone, and another one is width Nzw (Nzw>Nzn) used fordetermining where the lens is in order to catch up with the object at alow speed. Nzw is set as the value with the results of the pulse countcomparison value ZAFC multiplied by "j" (j>1), on the other hand, Nznvaries in accordance with the rotating quantity calculated. First ofall, there is provided a maximum rotating quantity N₁ counted for thetime in which it takes to stop for the motor MO from the rotatingcondition at the maximum speed by braking. Next, there also is provideda maximum rotating quantity N₂ of the motor MO counted for the time inwhich it takes to rotate at the maximum speed for the motor MO from thestop condition. Then in case the calculated rotating quantity Δn>N₁ +N₂=X₁, N₁ is set as the near focus zone Nzn. On the other hand, in caseΔn<N₁ +N₂, N₁ is set as Nzn. In this case, the motor MO is braked beforethe motor MO rotates at the maximum speed, therefore, after the rotationspeed of the motor MO reaches a low speed early, the lens is moved tothe focus position at the low speed. Therefore, it causes a problem inthat it takes a long time for the lens to reach the focus position,particularly in the condition that Δn approximates N₁. At the step No.151, in case the defocus count value Δn is more than X₁, the maximumvalue N₁ (X₁ >N₁) is set as the width Nzn of the near focus zone.Conversely, in case Δn is less than or equal to X₁, the value multipliedthe defocus count value Δn by "d" (d<1) is set as Nzn. At the step No.154, the comparison value with the results of the count value ZAFCmultiplied by "j" (j>1) set as the width Nzw of the near zone used forcatching up with the object. (Nzn<Nzw) Next, it is determined whetherthe focus flag AFIFF is "1" or not. In case the focus flag AFIFF is "1",the program flow goes to the step No. 156. On the other hand, in casethe flag AFIFF is not "1", it is determined whether the first out flagFOF is "1" or not. In case the first out flag FOF is "1", the programflow goes to the step No. 156. In case the first out flag FOF is not"1", the defocus count value Δn is set as the former defocus count valueΔnL. At the step No. 156, it is determined whether the high light flagHLF is "1" or not, in case the flag HLF is not "1", the program flowgoes to the step No. 159 without executing the steps No. 157 through No.160. Then the defocus count value Δn is set as the former defocus countvalue, the program flow goes to the step No. 164.

At the step No. 156, in case the high light flag HLF is "1", the programflow goes to the step No. 157. Then the difference between the formerdefocus count value ΔnL and the present defocus count value Δn, that is,the changed quantity Δ² n of the defocus count value is calculated.Next, at the step No. 158, it is determined whether the changed quantityΔ² n is less than a predetermined quantity L₁. In case Δ² n is less thanor equal to L₁, the program flow goes to the step No. 159 in the sameway of the case that the flag HLF has been reset. On the other hand, atthe step No. 158, in case the changed quantity Δn is more than thepredetermined quantity L₁, the program flow goes to the step No. 160.Then it is determined whether the first out flag FOF is "1", in case theflag FOF is not "1", the program flow goes to the step No. 161. The AFmicrocomputer MC₂ outputs the stop signal to the motor MO, the motorflag MOF is reset at the step No. 162, then the first out flag FOF isset and the program flow goes back to the step No. 36 in order tomeasure again. At the step No. 160, in case the first out flag FOF is"1", the program flow goes to the step No. 164. The above operation ofcalculating the changed quantity Δ² n and comparing Δ² n with thepredetermined quantity L₁ are performed in order to prevent fromresponding as a large defocus quantity when the large defocus quantityis suddenly calculated through an error on the condition of catching upwith the object.

At the step No. 164, the first out flag FOF is reset and also the focusflag AFIFF is reset. Next, at the step No. 165, it is determined whethera near zone flag NZF is "1". In case the near zone flag NZF is "1", theprogram flow goes to the step No. 170, on the other hand, in case thenear zone flag NZF is not "1", the program flow goes to the step No.166. The above determination of the near zone flag NZF is performed inorder to enlarge the range at which the motor MO rotates at a low speedduring the catching up mode after the lens has entered into the range ofthe near zone. Therefore, at the step No. 166, the defocus count valueΔn is compared with the narrower near zone count value Nzn, and at thestep No. 170 the defocus count value Δn is compared with the wider nearfocus zone count value Nzw. At the steps No. 166 or No. 170, in case itis determined that the defocus count value Δn is less than or equal tothe near zone count value Nzn or Nzw, the program flow goes to the stepNo. 167, then the near zone flag NZF is set. After that, the AFmicrocomputer MC₂ outputs "Low" to the terminal P₆ in order to make themotor control circuit MCC control so that the motor MO rotates at a lowspeed. At the step No. 159, the defocus count value Δn is loaded in thecounter and the program flow goes to the step No. 166. At the steps No.166 or No. 170, in case it is determined that the defocus count value Δnis more than the near zone count value Nzn or Nzw, the program flow goesto the step No. 171, then the near zone flag NZF is reset. Next, at thestep No. 172, the AF microcomputer MC₂ outputs "High" to the terminal P₆in order to make the motor control circuit MCC control so that the motorMO rotates at a high speed. At the step No. 173, the value subtractedthe near zone count value Nzn from the defocus count value Δn is loadedto the counter, and the program flow goes to the step No. 175. In FIG.10, the steps No. 175 through No. 182 are the operation performed whenthe lens is at the end position. At the step No. 175, it is determinedwhether a terminal flag TEF is "1" or not. In case the lens is not atthe end position, i.e. ∞ position, therefore the terminal flag TEF isnot "1", then the program flow goes to the step No. 183. On the otherhand, when the lens is at the end position, i.e. ∞ position, thereforethe terminal flag TEF is "1", then the program flow goes to the step No.176. At the step No. 176, the defocus direction is determined. In casethe image of the object is out of focus forward, the program flow goesto the step No. 177. On the other hand, in case the image of the objectis out of focus backward, the program flow goes to the step No. 178.Then in the both cases, a terminal position flag TPF is checked. Whenthe terminal position flag TPF is "1", the lens is at the nearest endposition to the object. On the other hand, when the terminal positionflag TPF is not "1", the lens is at the ∞ end position. At the step No.177, in case the terminal position flag TPF is not "1", the lens is atthe ∞ position and is in a front focus. Therefore, the lens cannot bemoved toward the body of the camera, the program flow goes to the stepNo. 180. In case the terminal position flag TPF is "1", the lens is atthe nearest end position to the object and is in a front focus, that is,the lens can be moved toward the body of the camera. Then the programflow goes to the step No. 179 in order to make the motor MO rotate. Onthe other hand, at the step No. 178, in case the terminal position flagTPF is "1", the lens is at the nearest end position to the object and isin a rear focus, the lens cannot be moved toward the object. Then theprogram flow goes to the step No. 180. In case the terminal positionflag TPF is not "1", when the lens is at the farthest end position fromthe object and is in a rear focus, the lens can be moved toward theobject. Then the program flow goes to the step No. 179. At the steps No.180 through No. 182, all the display of the focus condition and the outof focus condition is turned off, then the program flow goes back to thestep No. 36 in order to measure again. At the step No. 179, the terminalflag is reset. Next, the motor flag MOF is checked at the step No. 183.In case the motor flag MOF is "1", when the motor has already beenrotating, the program flow goes back to the step No. 36.

At the step No. 183, in case the motor flag MOF is not "1", when themotor MO stops, the motor flag MOF is set at the step No. 184. Next, atthe step No. 185, the defocus direction is determined. In case the lensis in a front focus, the program flow goes to the step No. 186. On theother hand, in case the lens is in a rear focus, then the program flowgoes to the step No. 188. At the step No. 186, the driving directionflag DDF is set. On the other hand, at the step No. 188, the drivingdirection flag DDF is reset. At the step No. 187 after the step No. 186,the AF microcomputer MC₂ outputs a "Low" signal to the terminal P₄. Onthe other hand, at the step No. 189 after the step No. 188, the AFmicrocomputer MC₂ outputs a "Low" signal to the terminal P₅. In theabove both cases, the AF microcomputer MC₂ makes the motor MO rotate inthe required direction. At the step No. 190 after the step No. 187 orNo. 189, the AF microcomputer MC₂ waits until the speed of the rotationof the motor MO attains predetermined stable speed, then the programflow goes back to the step No. 36.

The length of the wait time in the step No. 190 may be a predeterminedlength of time by considering the amount of the load of theinterchangeable lens and/or the drive voltage of the motor MO. In thestep No. 190, as a way of deciding whether or not the flow should go tothe step No. 36, the motor speed may be detected. Thus if it is detectedthat the motor speed reaches a predetermined value, the program flowgoes to the step No. 36.

The operation from the step No. 191 is the interruption to the interruptterminal it₃. The interruption to the interrupt terminal it₃ isperformed in order that the microcomputer MC₁ orders to start theshutter release motion to the AF microcomputer MC₂. After the AFmicrocomputer MC₂ receives the interrupt signal at the interruptterminal it₃, the program flow goes to the step No. 191. At the step No.191, it is determined whether the terminal P₁₂ is "High". In case theterminal P₁₂ is "High", when the single mode is selected, the programflow goes to the step No. 192. Then the AF microcomputer MC₂ outputs a"High" signal to the terminal P₈ in order to disable an in focusindicating buzzer. Next, at the step No. 193, the AF microcomputer MC₂outputs a "High" signal to the terminals P₄ and P₅ and makes the motorMO stop. At the step No. 194, the motor flag MOF is reset. Then the AFmicrocomputer MC₂ waits until the signal INREL becomes "High". In casethe signal INREL is "High", the program flow returns to the step No.148. At the step No. 191, in case the terminal P₁₂ is "Low", under thenormal mode, the program flow goes to the step No. 196. Then the afterrelease flag AFRF is set, then the AF microcomputer MC₂ outputs a "Low"signal to the terminal P₂ in order to stop charging in the CCD at thestep No. 197. Then the display condition is stored in a memory at thestep No. 198, and at the step No. 199, the AF microcomputer MC₂ outputsthe "High" signals to the terminals P₇, P₈ and P₉ in order to turn thedisplay off. Next, at the step No. 200, the AF microcomputer MC₂ outputsa "High" signal to the terminal P₁₆ in order to cancel a demand QTRQ ofthe serial data communication. Then at the step No. 201, the serialinterruption is inhibited. The AF microcomputer MC₂ outputs a "High"signal to the terminal P₁₄ in order to inform it to the microcomputerMC₁ that the shutter release operation is permitted and the AFmicrocomputer MC₂ outputs "High" to the terminal P₁₃. At the step No.204, the timer of the AF microcomputer MC₂ is reset. Next, the AFmicrocomputer MC₂ makes the timer start and the AF microcomputer MC₂waits until the timer counts a predetermined time T₀. As soon as thetimer counts the predetermined time T₀, the AF microcomputer MC₂ outputsa "Low" signal to the terminal P₁ at a predetermined time in order thatthe interface circuit INF begins to charge in the CCD. When the releaseoperation of the shutter sets about, the shutter used for obstructingthe light is closed and the light does not reach the CCD sensor MLMC.Therefore, the above integral operation is to store the charge in theCCD corresponding to the dark output. The program flow goes to the stepNo. 208, as soon as the timer counts the time T₁, the program flow goesto the step No. 209. At the step No. 209, it is determined whether theexposure time value Tv for photographing is more than a threshold valueTvL. In case the exposure time value Tv for photographing is more thanTvL, the AF microcomputer MC₂ makes the motor rotate continuouslywithout stopping. Then the motor MO is made to stop when the motor MOrotates for the driven time and the counter interruption is receivedbecause the counter interruption is permitted. The routine of thecounter interruption will be described later. The threshold value TvL isset by such a value that the photograph by the exposure operation is notbadly influenced even though the exposure is made while the lens isbeing moved. At the step No. 209, in case the value Tv for photographingis less than or equal to the threshold value TvL, the program flow goesto the step No. 210. Then the driving signal to the motor MO is turnedoff in order to stop the motor MO. Besides, the timer value T₀ and T₁are set in order to make the first curtain of the shutter in the camerabegin to run (at the step #91 in FIG. 3) after the motor MO is actuallymade to stop by "High" driving signals RRT and LRT. Then the motor flagMOF is reset at the step No. 211. The program flow goes to the step No.212, the AF microcomputer MC₂ waits until the timer counts the time T₂.As soon as the timer counts the time T₂, at the step No. 213, the AFmicrocomputer MC₂ outputs a "Low" signal to the terminal P₂ at apredetermined time in order to stop to charge in the CCD in connectionwith the dark output. Then at the step No. 214, the CCD data of the darkoutput is read and stored in a memory. After that, the AF microcomputerMC₂ waits the interruption.

In FIG. 6, the operation from the step No. 216 is the interruption tothe interrupt terminal it₂, which is the AF stop interruption caused bythe microcomputer MC₁. As soon as the it₂ interruption is received, theprogram flow goes to the step No. 216. Then the driving signal to themotor MO is turned off in order to make the motor MO stop. Next, the AFmicrocomputer MC₂ outputs a "High" signal to the terminal P₇, P₈ and P₉and turn the display off. At the step No. 218, the AF microcomputer MC₂outputs a "High" signal to the terminal P₁₆ and the AF microcomputer MC₂cancels the demand of the serial data communication. The program flowgoes to the step No. 219, the AF microcomputer MC₂ outputs a "Low"signal (the signal INSTP) to the terminal P₂ for a predetermined timeand stop charging in the CCD. At the step No. 220, the interruption tothe terminals except for the interrupt terminal it₁ and it₂ isinhibited, and at the step No. 221, the AF microcomputer MC₂ outputs a"High" signal to the terminal P₁₄ in order to inform the microcomputerMC₁ that the operation of the automatic focal distance control iscompleted. At the step No. 222, the flags to be reset are reset, theprogram flow goes to the step No. 223, then the AF microcomputer MC₂outputs a "Low" signal to the terminal P₁₃ and the program flow goes tothe power saving mode.

The routine of the counter interruption sets about from the step No. 241as shown in FIG. 11. As soon as the value counted down by each counterbecomes "0", the counter interruption sets about and the program flowgoes to the step No. 241. At the step No. 241, the driving signal to themotor MO is turned off. Next, at the step No. 242, the near zone flagNZF is checked. In case the flag NZF is not "1", the program flow goesto the step No. 243 in order to change the rotation speed of the motorMO from a high speed to a low speed. At the step No. 243, the AFmicrocomputer MC₂ outputs a "Low" signal to the terminal P₆ and the AFmicrocomputer MC₂ makes the motor control circuit MCC control the motorMO at a low speed. Next, at the step No. 244, the near zone count valueNzn is loaded to the counter. Then at the step No. 245, the near zoneflag NZF is set. At the steps No. 246 through No. 248, the drivingdirection flag DDF is checked, then the AF microcomputer MC₂ outputs"Low" to the terminal P₄ or P₅ in accordance with the said direction inorder that the motor MO rotates in accordance with the said direction.The program flow returns.

At the step No. 242, in case the near zone flag is "1", when the motorMO has rotated for a required driving time, the program flow goes to thestep No. 249, then the motor flag MOF is reset. Next, at the step No.250, the AF focus flag AFIFF is set. Then at the step No. 251, it isdetermined whether the terminal P₁₂ is "High". In case the terminal P₁₂is "High", the program flow returns to the step No. 145 in order toperform the focus control operation in the single mode. On the otherhand, in case the terminal P₁₂ is "Low", under the single mode, theprogram flow goes to the step No. 252, then the after release flag AFRFis checked. In case the after release flag is "1", the program flowreturns. On the other hand, in case the after release flag AFRF is not"1", the program flow goes to the step No. 141 in order to perform thefocus control operation.

In FIG. 11, the operation from the step No. 253 is the subroutine usedfor detecting whether the lens is at the end position or not. First ofall, at the step No. 253, the content of the counter is inputted to aregister n'. At the step No. 254, a counter value Ln', which is storedin a memory at the last detection of whether the lens is at the endposition or not, is compared with the counter value n' inputted at theabove step No. 253. In case n' equals to Ln', when the encoder has notoutputted any pulse during detecting whether the lens is at the endposition or not, the program flow returns to the step No. 256 and theoperation on the condition that the lens is at the end position isperformed. On the other hand, in case n' is not equal to Ln', when thelens has not reached the end position, n' is stored as Ln' and theprogram flow returns to the former routine.

The operation from the step No. 256 is the operation on the conditionthat the lens has reached the end position. At the step No. 256, thedriving signal to the motor MO is turned off and the motor MO is made tostop. Next, at the step No. 257, a low contrast scan flag LCFI ischecked. In case the flag LCFI is not "1", when scanning with the lowcontrast is not performed, the program flow goes to the step No. 258.Then the terminal flag TEF is set, and the motor flag MOF is reset atthe step No. 259. Next, at the step No. 260, the driving direction flagDDF is checked. In case the flag DDF is "1", the program flow goes tothe step No. 261, then the terminal position flag TPF is reset and thelens is at the farthest end position from the object. On the other hand,in case the driving direction flag DDF is not "1", the program flow goesto the step No. 262, then the terminal position flag TPF is set andthereby it is indicated that the lens is at the nearest end position tothe object. Then the terminal P₁₂ is checked. In case the terminal P₁₂is "Low", under the single mode, the program flow goes to the step No.264, then the AF microcomputer MC₂ outputs a "High" signal to theterminals P₇ and P₉ and the display of the defocus direction is turnedoff. Then the program flow returns to the step No. 36 in order tomeasure the light again. On the other hand, if the terminal P₁₂ is"High", under the single mode, the program flow goes back to the stepNo. 36.

At the step No. 257, in case the low contrast scan flag LCFI is "1",when scanning with the low contrast is performed, the program flow goesto the step No. 265, then the low contrast flag LCF₂ is checked. In casethe low contrast flag LCF₂ is not "1", the program flow goes to the stepNo. 269 in order to scan conversely. Then the low contrast flag LCF₂ isset and the driving direction flag DDF is converted at the step No. 270so that the flag DDF becomes "0" when the flag DDF is "1" and the flagDDF becomes "1" when the flag DDF is "0". Next, at the steps No. 271through No. 273, the driving direction flag DDF is checked and the AFmicrocomputer MC₂ outputs the driving signal to the motor MO inaccordance with the said direction. Then the program flow goes back tothe step No. 36 in order to measure the light again. At the step No.265, in case the low contrast flag LCF₂ is "1", when scanning with thelow contrast is completed, the program flow goes to the step No. 266,then the low contrast flag LCF₃ is set and scanning with the lowcontrast is inhibited. At the step No. 267, the low contrast flags LCF₁and LCF₂ are reset, and at the step No. 268, the motor flag MOF is resetand thereby it is indicated that the motor stops. Then the program flowgoes back to the step No. 36 in order to measure again.

Moreover, in order that the control apparatus for the automatic focuscontrol is operated for itself for the check and adjustment during themanufacturing process in FIG. 1, the following steps is added to theabove flow charts of the AF microcomputer MC₂. In this case, the lenswith a particular fixed focal distance is mounted in order to check andadjust the control part for controlling the focal distanceautomatically. At the step No. 21, in case the flag AFRF is "1", it isdetermined whether the terminal P₁₂ is "High" or not. In case theterminal P₁₂ is "Low", the program flow goes to the step No. 27. On theother hand, the terminal P₁₂ is "High", when the check mode has beenselected, the program flow goes back to the step No. 36. Then at thestep No. 52, it is determined that the terminal P₁₂ is "High", and it isdetermined whether the input and output port P₇ is in the input mode orthe output mode. In case the input and output port P₇ is in the inputmode, when the single mode shown in FIG. 5 has been selected, theprogram flow goes to the step No. 54. On the other hand, in case theinput and output port P₇ is in the output mode, the circuit shown inFIG. 1 is in the check mode and the information is fixedly stored in theROMs in the microcomputers MC₁ and MC₂. The conversion factor of theabove particular lens is set for calculating and the program flow goesto the step No. 60. Moreover, at the step No. 139, it is determined that"High" is inputted to the terminal P₁₂, and it is determined whether theterminal P₇ is in the input mode or the output mode. In case theterminal P₇ is in the input mode, when the single mode has beenselected, the program flow goes to the step No. 145. On the other hand,in case the terminal P₇ is in the output mode, the program flow goes tothe step No. 141.

By adding the above steps and inputting a start signal of the AFoperation, even though the circuit is so arranged as shown in FIG. 1,the AF microcomputer MC₂ operates for itself having no relation with themicrocomputer MC₁ and the control part for the automatic focus controlcan be operated for itself for the check and adjustment of the controlpart. Moreover, at the step No. 52, it is determined that the terminalP₁₂ is "High" and the terminal P₇ are in the output mode, the data ofthe CCD is outputted from input and output ports not shown or the outputterminal of the serial data. Next, the data used for adjusting are readand the program flow goes to the step No. 60. If the focus quantity Δεis outputted for checking and adjusting the control circuit after thestep No. 60 is performed and the terminal P₇ is made to be in the outputmode, it may be easy to check and adjust the control circuit.

Although the AF microcomputer MC₂ is set about only under the FA modewhen the switches TSS, ASS, ISS MOSS, UPS and DOS are operated in thesteps #4 through #11 in FIG. 2, in place of this method, the followingoperation may be employed. Namely, the AF microcomputer MC₂ is alwaysset about simultaneous with the start of the control microcomputer MC₁but the lens is not driven so far as the one of the switches TSS, ASS,ISS, MOSS, UPS and DOS causes to start the microcomputer MC₁ in the AFmode. In addition, when the camera is set in the operative condition bythe operation of the those set switches under AF mode, it is possible toenable the display as in the FA mode.

Also in the step No. 86 when the reset of the low contrast flag CF₁ isdetected, the program flow may be shifted to the step No. 36 omittingthe steps Nos. 87 to 92. According to this arrangement, the photographiclens may be moved up to the in focus position (referred to a first infocus position) based on the data just before the change of the contrasteven though the contrast of the object is suddenly changed to the lowcontrast, and in case the contrast measured by the camera is restored tothe initial value before the photographic lens reaches the first infocus position, the lens may be moved up to in focus position inaccordance with a new data obtained based on the restored contrast.However in case the contrast is not restored i.e., the low contrast iscontinued before the photographic lens reaches the first in focusposition, the photographic lens is moved up to the first in focusposition.

Table 5 represents the relation signals and their contents in the AFmicrocomputer MC₂, while Table 6 represents the contents of flagsreferred to in the flow program shown in FIGS. 6 through 11.

                                      TABLE 5    __________________________________________________________________________    The signals in the AF microcomputer MC2    Port in    micro-         Normal (camera) mode      Single (lens itself) mode    computer         Signal              Content              Signal                                        Content    __________________________________________________________________________    P.sub.0         INEN the integral completion signal                                   INEN the integral signal completion                                        signal              from the interface circuit INF                                        from the interface circuit INF    P.sub.1         INSTA              the integral start signal                                   INSTA                                        the integral start signal              to the interface circuit INF                                        to the interface circuit INF    P.sub.2         INSTP              the integral stop signal                                   INSTP                                        the integral stop signal              to the interface circuit INF                                        to the interface circuit INF    P.sub.3         ADEN the A/D conversion data input timing signal                                   ADEN the A/D conversion data input timing                                        signal              from the interface circuit INF                                        from the interface circuit INF    D.sub.0         ADD  the input bus for the CCD output                                   ADD  the input bus for the CCD output              from the interface circuit INF                                        from the interface circuit INF    P.sub.4         RRT  the clockwise rotation signal                                   RRT  the clockwise rotation signal              to the motor driving circuit MCC                                        to the motor driving circuit MCC    P.sub.5         LRT  the counterclockwise rotation signal                                   LRT  the counterclockwise rotation signal              to the motor driving circuit MCC                                        to the motor driving circuit MCC    P.sub.6         GOV  the speed switching signal                                   GOV  the speed switching signal              to the motor driving circuit MCC                                        to the motor driving circuit MCC    P.sub.8         IFLS the driving signal to the light emitting                                   IFBZ the driving signal to the buzzer              diode for displaying the in focus condition                                        for displaying the in focus                                        condition    P.sub.12         SNS  the single/normal mode switching signal                                   SNS  the single/normal mode switching                                        signal    P.sub.7         RFLS the driving signal to the LED for displaying                                        the input bit of defocus quantity -              the defocus direction in a rear focus                                        encoder pulse count conversion                                        factor    P.sub.9         FFLS the driving signal to the LED for displaying                                        the input bit of defocus quantity -              the defocus direction in a front focus                                        encoder pulse count conversion                                        factor    P.sub.10         FLS  the focus lock signal     the input bit of defocus quantity -                                        encoder pulse count conversion                                        factor    P.sub.11         AMS  the AF/FA mode switching signal                                        the input bit of defocus quantity -                                        encoder pulse count conversion                                        factor    P.sub.13         STPOK              the clock pulse stop signal                                        the input bit of defocus quantity -              to the microcomputer MC.sub.1                                        encoder pulse count conversion                                        factor    P.sub.14         AFEN the AF completion signal  the input bit of defocus quantity -              to the microcomputer MC.sub.1                                        encoder pulse count conversion                                        factor    P.sub.15                            the input bit of defocus quantity -                                        encoder pulse count conversion                                        factor    P.sub.16         DTRQ the demand signal of the serial                                        the input bit of defocus quantity -              communication to the microcomputer MC.sub.1                                        encoder pulse count conversion                                        factor    CLI.sub.0         ENCL the encoder output pulse signal                                   ENCL the encoder output pulse signal              from the encoder circuit ENCC                                        from the encoder circuit ENCC    it.sub.1         AFSTA              the AF start interruption signal                                        not use              from the microcomputer MC.sub.1    it.sub.2         AFSTP              the AF stop interruption signal                                        not use              from the microcomputer MC.sub.1    it.sub.3         INREL              the release interruption signal                                   INREL                                        the release interruption signal              from the microcomputer MC.sub.1                                        from the microcomputer MC.sub.1    SICK.sub.0         SICK the clock pulse for the serial communication                                        not use              from the microcomputer MC.sub.1    SIIN.sub.0         SIBS.sub.1              the serial data           not use              from the microcomputer MC.sub.1    STCLIN         STCL the driving clock pulse                                   STCL the driving clock pulse              to the AF microcomputer MC.sub.2                                        to the AF microcomputer    __________________________________________________________________________                                        MC.sub.2

                                      TABLE 6    __________________________________________________________________________    The flag used in the flow charts    Flag code         Name of flag                    Content          "0" state "1" state    __________________________________________________________________________    FMF  Focus mode flag                    distinction of the AF or FA mode                                     the AF mode                                               the FA mode    FLF  Focus lock flag                    determination of the focus                                     not on the focus                                               on the focus lock                    lock condition   lock condition                                               condition    MOF  Motor flag if the motor is rotating                                     motor stop                                               motor rotating    LCF.sub.0         Low contrast flag 0                    if the object has the low contrast                                     normal condition                                               low contrast    LCF.sub.1         Low contrast flag 1                    if scanning with the low contrast                                     not scanning                                               scanning                    is performed    LCF.sub.2         Low contrast flag 2                    if forward or backward scanning                                     forward scanning                                               backward scanning                    is performed    LCF.sub.3         Low contrast flag 3                    inhibition of scanning with the                                     permission of                                               inhibition of                    low contrast     scanning  scanning    AFRF After release flag                    if the release operation                                     not performed                                               performed                    is performed    LLF  Low light flag                    if the object has low brightness                                     normal condition                                               low brightness    AFIFF         AF in focus flag                    if the image of the object is in                                     out of focus                                               in focus                    focus in the AF mode    DDF  Driving direction flag                    the driving direction                                     toward the object                                               toward the body of                                               the camera    FOF  First out flag                    if the sudden big change in the                                     normal condition                                               sudden big change                    the defocus value occurs    NZF  Near zone flag                    if the lens is inside or outside                                     outside of the                                               inside of the                    of the near zone near zone near zone    TEF  Terminal flag                    if the lens is at the end position                                     not at the end                                               at the end position                                     position    TPF  Terminal position flag                    the side of end position of                                     ∞ focus side                                               closest focus side                    the lens    HLF  High light flag                    if the object has high brightness                                     not high brightness                                               high brightness    __________________________________________________________________________

What is claimed is:
 1. An automatic focus control camera having meansfor varying the focus condition comprising:means for obtaininginformation necessary for automatic focus control, including means forsensing a focus condition and means for generating a data signalindicative of the necesary degree of focus adjustment required inresponse to the sensing means, said obtaining means requiring a timeperiod from the sensing of the focus condition until the generation ofthe data signal; means for providing a driving power for varying thefocus adjustment in accordance with the data signal; means for directingsaid obtaining means to operate when the driving power is not beingprovided and also when the driving power is being provided; meansoperative when the driving power is being provided, for modifying theeffect of the data signal with the degree of focus adjustment expectedto be required during a predetermined application of driving power tothe means for varying the focus condition; and means for interruptingthe operation of said obtaining means and said modifying means for aperiod of time beginning from an initiation of providing the drivingpower, the period of time being greater than the time required from theinitiation of the focus adjustment until an attainment of apredetermined speed of a focus adjustment movement caused by the drivingpower.
 2. The automatic focus control camera according to claim 1,further comprising means for subtracting the actual degree of focusadjustment caused by the driving power from the degree of focusadjustment represented by the data signal generated before the provisionof the driving power, and means for preparing a reference data signal,wherein said providing means includes means responsive to any remaindervalue resulting from the subtraction and the reference data signal forreducing the driving power when the remainder value becomes less thanthe reference data signal, and wherein said preparing means includesmeans for changing the reference data signal in accordance with the datasignal generated by said generating means before the provision of thedriving power.
 3. The automatic focus control camera according to claim1, further comprising means for preparing a first reference level and asecond reference level greater than the first one, and wherein saidproviding means includes means for varying the driving power with aselected one of the first and second reference levels and for reducingthe driving power when the data signal is less than the selectedreference level, and means for selecting the first reference level withthe driving power not reduced, and the second reference level with thedriving power reduced, respectively.
 4. The automatic focus cameraaccording to claim 1, further comprising means for deciding whether thedata signal of said obtaining means is reliable, means for controllingsaid providing means to provide the driving power in accordance with apredetermined signal in place of the data signal when said decidingmeans decides that the data signal is not reliable, means forinvestigating whether the driving power is provided, and meansresponsive to said investigating means for disabling said controllingmeans when the driving power is provided.
 5. The automatic focus controlcamera according to claim 1, wherein said directing means includes meansfor repeatedly directing said obtaining means to operate, means forfinding a difference between a pair of successively generated datasignals and means responsive to said finding means for causing saidproviding means to respond to the later one of the pair of data signalswhen the difference is within a predetermined range and for causing saidproviding means to respond to next data signal generated in successionto the pair of data signals when the difference is over thepredetermined range.
 6. The automatic focus control camera according toclaim 1, further comprising means for preparing a first reference levelrepresentative of a first level of defocusing degree and a secondreference level representative of a second level of defocusing degreegreater than the first one, means for informing whether or not ateleconverter is used with the camera, and means responsive to saidinforming means for selecting the first reference level when theteleconverter is not used, and for selecting the second reference levelwhen the teleconverter is used, wherein said providing means includesmeans for comparing the data signal with the selected one of the firstand second reference levels and for deciding when the focus adjustmentis in the infocus condition when a level of the defocusing degreerepresented by the data signal is less than the level of the defocusingdegree represented by the selected reference level.
 7. The automaticfocus control camera according to claim 1, further comprising means forperforming a camera exposure operation, first means for controlling theoperation of said obtaining means, second means for controlling theoperation of said obtaining means, sequence control means forcontrolling said performing means and said first controlling means, andmeans for selecting between said first and second controlling means,whereby the obtaining means operates under the control of said sequencecontrol means in a accordance with a total camera operation sequencewhen said first controlling means is selected, and the obtaining meansalso operates independently from the control of said sequence controlmeans when said second controlling means is selected.
 8. The automaticfocus control camera according to claim 1, further comprising means forinforming of the focus condition in response to said obtaining means andfor switching between an automatic focus control mode in which saidproviding means is operative and a manual focus control mode in whichsaid providing means is inoperative, means for calculating an exposurecontrol data, a first manually operable member for a shutter releaseoperation, a second manually operable member for setting an exposureinformation, first means for enabling said calculating means in responseto a manipulation of either of said first and second manually operablemembers in either of the automatic and manual focus control modes,second means for enabling said providing means in response to amanipulation of said first manually operable member with no response tothat of said second manually operable member in the automatic focuscontrol mode, and third means for enabling said informing means inresponse to a manipulation of either of said first and second manuallyoperable members in the manual focus control mode.
 9. An automatic focuscontrol camera comprising:means for obtaining information necessary forautomatic focus control, the information being indicative of thenecessary degree of focus adjustment; means for providing a drivingpower for focus adjustment in accordance with the information; means fordirecting said obtaining means to operate when the driving power is notprovided; means for detecting a remainder value obtainable bysubtracting the actual degree of focus adjustment caused by the drivingpower from the degree of focus adjustment represented by the informationobtained before the provision of the driving power; means for preparinga reference data; means responsive to the remainder value and thereference data for reducing a speed of focus adjustment caused by thedriving power when the remainder value becomes less than the referencedata; and means for changing the reference data in accordance with theinformation obtained before the provision of the driving power.
 10. Theautomatic focus control camera according to claim 9, wherein saidchanging means includes means for comparing a predetermined informationwith the information obtained before the provision of the driving powerand means responsive to said comparing means for maintaining thereference data at a constant value when the information from theobtaining means is greater than the predetermined information and forreducing the reference data from the constant value when the informationfrom the obtaining means is than the predetermined information.
 11. Theautomatic focus control camera according to claim 10 further includingmeans for braking the driving power, wherein the constant valuecorresponds to the degree of focus adjustment expected to occur from thetime of the braking of the focus adjustment at its maximum speed until acomplete stopping of the focus adjustment.
 12. An automatic focuscontrol camera comprising:means for obtaining information necessary forautomatic focus control, the information relating to a level of thedefocusing degree and a direction of the defocus; means for providing adriving power for focus adjustment in accordance with the information;means for preparing a first reference level and a second reference levelgreater than the first one, both the first and second reference levelsbeing greater than a level of defocusing degree which is regarded as anin-focus condition; means for comparing the information with a selectedone of the first and second reference levels and for reducing thedriving power of said providing means when the level of the defocusingdegree represented by the information is less than the level of thedefocusing degree represented by the selected reference level; and meansfor selecting the first reference level with the driving power notreduced, and the second reference level with the driving power reduced,respectively.
 13. An automatic focus control camera having means forvarying the focus condition of the camera comprising:means for obtaininginformation necessary for automatic focus control; means for providing adriving power in accordance with the information to the means forvarying the focus condition; means for repeatedly directing saidobtaining means to operate when the driving power is not provided andalso when the driving power is provided; means for deciding whether theinformation of said obtaining means is reliable; means for controllingsaid providing means to provide the driving power in accordance with apredetermined signal in place of the information when said decidingmeans decides that the information is not reliable, so as to seekanother position of focus adjustment at which the information of saidobtaining means is reliable; means for investigating whether the drivingpower is provided in accordance with the information; and meansreponsive to said investigating means for disabling said controllingmeans when the driving power is provided.
 14. The automatic focuscontrol camera according to claim 13, wherein said obtaining meansincludes means for sensing a contrast of the image, and wherein saiddeciding means includes means for regarding the information unreliablewhen the contrast is less than a predetermined required level.
 15. Theautomatic focus control camera according to claim 13, wherein saiddisabling means includes means for interrupting the provision of thedriving power, and for directing said obtaining means to operate withthe focus adjustment stopped, and also for enabling said providing meansagain, in place of the operation of said controlling means.
 16. Theautomatic focus control camera according to claim 13, wherein saiddisabling means includes means for enabling said providing means tocontinue the provision of driving power in accordance with theinformation obtained before the deciding means functions, in place ofthe operation of said controlling means.
 17. An automatic focus controlcamera comprising:means for obtaining information necessary forautomatic focus control; means for providing a driving power for focusadjustment in accordance with the information; means for repeatedlydirecting said obtaining means to operate; means for finding adifference between a pair of successively obtained informations; andmeans responsive to said finding means for causing said providing meansto respond to the later one of the pair of informations when thedifference is within a predetermined range and for causing saidproviding means to respond to the next information obtained insuccession to the pair of informations when the difference is over thepredetermined range.
 18. The automatic focus control camera according toclaim 17, wherein said finding means includes means for storing theinformation from said obtaining means, and means for comparing thestored information with the information obtained in succession to thestored information to find the difference therebetween.
 19. Theautomatic focus control camera according to claim 17, further comprisingmeans responsive to said finding means for interrupting the provision ofthe driving power when the difference is over the predetermined range sothat the next information is obtained without the provision of thedriving power.
 20. The automatic focus control camera according to claim17, further comprising means for measuring light from an object to befocused to make said directing means prolong a repetition period of itsdirections as the measured light intensity decreases, and means fordetecting whether the measured light intensity is less than apredetermined level, wherein said causing means is further responsive tosaid detecting means for causing said providing means to respond to thelater one of the pair of informations when the less intensity isdetected even if the difference is over the predetermined range.
 21. Theautomatic focus control camera according to claim 20, further comprisingmeans responsive to said finding means and said detecting means forinterrupting the provision of the driving power when the difference isover the predetermined range and the measured intensity is greater thanthe predetermined level, so that the next information is obtainedwithout the provision of the driving power.
 22. An automatic focuscontrol camera comprising:means for obtaining information necessary forautomatic focus control, the information being indicative of a level ofthe defocusing degree; means for providing a driving power of focusadjustment in accordance with the information; means for directing saidobtaining means to operate; means for preparing a first reference levelrepresentative of a first level of defocusing degree and a secondreference level representative of a second level of defocusing degreegreater than the first one; means for informing whether or not ateleconverter is used with the camera; means responsive to saidinforming means for selecting the first reference level when theteleconverter is not used, and for selecting the second reference levelwhen the teleconverter is used; and means for comparing the informationwith the selected one of the first and second reference levels and fordeciding that the focus adjustment is in an in-focus condition when thelevel of the defocusing degree represented by the information is lessthan the level of the defocusing degree represented by the selectedreference level.
 23. The automatic focus control camera according toclaim 22, wherein said preparing means includes means for determiningthe first reference level in accordance with data representative ofaperture value, and for determining the second reference level inaccordance with the data representative of aperture value with apredetermined value added.
 24. A camera capable of automaticallydetecting the focus condition comprising:means for obtaining informationnecessary for automatic detecting of the focus condition; means forstarting a camera exopsure operation; first means for controlling theoperation of said obtaining means; second means for controlling theoperation of said obtaining means; sequence control means forcontrolling said starting means and said first controlling means; andmeans for selecting between said first and second controlling means,whereby said obtaining means operates under the control of said sequencecontrol means in accordance with a total camera operation sequence whensaid first controlling means is selected, and said obtaining means alsooperates without the control of said sequence control means when saidsecond controlling means is selected.
 25. The camera according to claim24, further comprising means for providing a driving power for automaticfocus adjustment in accordance with the information, said providingmeans being also under the control of one of said first and secondcontrolling means selected by said selecting means.
 26. An automaticfocus control camera comprising:means for obtaining informationnecessary for focus control; means for providing a driving power forautomatic focus adjustment in accordance with the information; means forproviding information from said obtaining means; means for switchingbetween an automatic focus control mode in which said driving powerproviding means is operative and a manual focus control mode in whichsaid driving power providing means is inoperative; means for calculatingan exposure control data; a first manually operable member for a shutterrelease operation; a second manually operable member for settingexposure information; first means for enabling said calculating means inresponse to a manipulation of either of said first and second manuallyoperable members in either of the automatic and manual focus controlmodes; second means for enabling said providing means in response to amanipulation of said first manually operable member with no response tothat of said second manually operable member in the automatic focuscontrol mode; and third means for enabling said information providingmeans in response to a manipulation of either of said first and secondmanually operable members in the manual focus control mode.